Why do some English-language texts refer to the Buddha as "Lord"?

There is one sense in which the Buddha is a lord in the wikipedia sense. He is the lord of the truth, the authority of the four Noble Truths:

MN18:13.1: “Addhāvuso kaccāna, bhagavā jānaṁ jānāti, passaṁ passati, cakkhubhūto ñāṇabhūto dhammabhūto brahmabhūto, vattā pavattā, atthassa ninnetā, amatassa dātā, dhammassāmī tathāgato.

MN18:13.1: “Certainly he is the Buddha, who knows and sees. He is vision, he is knowledge, he is the truth, he is holiness. He is the teacher, the proclaimer, the elucidator of meaning, the bestower of the deathless, the lord of truth, the Realized One.

Here, dhammassāmī is lord of the dhamma (see comments below as well...)

And here is an example of Lord Buddha speaking as a lord:

SN12.26:3.4: Saying this you would repeat what I have said, and not misrepresent me with an untruth. You would explain in line with my teaching, and there would be no legitimate grounds for rebuke and criticism.

It depends on what translators choose to use.

Ven. Thanissaro's translation of AN 8.26 says:

"Lord, to what extent is one a lay follower?"

Ven. Sujato's translation of AN 8.26 says:

“Sir, how is a lay follower defined?”

It turns out that the Pali sentence is:

“kittāvatā nu kho, bhante, upāsako hotī”ti?

In this case, the term "bhante" is translated as "lord" by Ven. Thanissaro and as "sir" by Ven. Sujato.

In this sutta (MN 147), "bhante" is translated as "venerable sir" by Ven. Bodhi.

Of course, "venerable sir" is the best translation.

Usually, the Buddha is addressed as "bhante" (venerable sir) in the second person and as "bhagavā" (blessed one) in the third person. This is in reference to Pali suttas.

All three translators mentioned above, translate "bhagavā" as "blessed one". The Sanskrit version of this word, "bhagavan" is commonly translated in Hinduism as "Lord", like "Bhagavan Krishna" (Lord Krishna). But the original meaning in Sanskrit is also "blessed one".

For what it's worth the word "Lord" would usually imply to me (in a religious, Christian, and/or secular context) "obedience" -- i.e. you or I would say it mostly to imply obedience; and not (or even more than) in order to imply that the person is a benefactor, a generous patron. I'm pretty sure that "obedience" is a Christian and/or Muslim understanding (e.g. "[may] thy will be done").

That (i.e. obedience) is how I read MN 147

Then the Blessed One, early in the morning, put on his robes and, carrying his bowl & outer robe, went into Savatthi for alms. Having gone for alms in Savatthi, after the meal, returning from his alms round, he said to Ven. Rahula, "Fetch your sitting cloth, Rahula. We will go to the Grove of the Blind to spend the day."

Responding, "As you say, lord," to the Blessed One, Ven. Rahula, carrying his sitting cloth, followed behind the Blessed One.

The "lord" in that translation is Ven. Thanissaro's translation of bhante -- compare:

• Ven. Thanissaro

  Responding, "As you say, lord," to the Blessed One, Ven. Rahula, carrying his sitting cloth, followed behind the Blessed One.

• Ven. Sujato

  “Yes, sir,” replied Rāhula. Taking his sitting cloth he followed behind the Buddha.

• Pali

  “Evaṃ, bhante”ti kho āyasmā rāhulo bhagavato paṭissutvā nisīdanaṃ ādāya bhagavantaṃ piṭṭhito piṭṭhito anubandhi.

IMO that (i.e. that it implies some obedience -- or "deference", "submission") is especially true when it's used in the vocative.

The same word -- bhante -- is used by the way in DN 16, among the Buddha's last words:

After my passing, mendicants ought not address each other as ‘reverend’, as they do today. A more senior mendicant ought to address a more junior mendicant by name or clan, or by saying ‘reverend’. A more junior mendicant ought to address a more senior mendicant using ‘sir’ or ‘venerable’.

Yathā kho panānanda, etarahi bhikkhū aññamaññaṃ āvusovādena samudācaranti, na kho mamaccayena evaṃ samudācaritabbaṃ. Theratarena, ānanda, bhikkhunā navakataro bhikkhu nāmena vā gottena vā āvusovādena vā samudācaritabbo. Navakatarena bhikkhunā therataro bhikkhu ‘bhante’ti vā ‘āyasmā’ti vā samudācaritabbo.

I'm not sure why he translates āvuso there as "reverend" -- I'm used to thinking of it as meaning 'friend'.

But the point is, here again Ven. Sujato translates bhante as "sir" -- and the Buddha tells the monks to use that form (or āyasma ) when they address senior monks (and lay people may use it for any monk) -- it's not a form reserved exclusively or specifically for the Buddha himself.

Or if not exactly "obedience", when people do use it I think it's sometimes polite and conventional -- a sign of respect -- and/or related to the practice of exclaiming (or feeling) "Sadhu!" (see e.g. the answers to this topic).

Another thing is that bhante and similar words are pretty explicitly honorifics.

And that is a sense which the word "Teacher" doesn't accurate translate, even if you prefer it because you imagine that would please other people, who don't want to express especial honour or devotion -- like using "comrade" in a communist society to emphasise that everyone is socially equal (e.g. "As you say, comrade teacher"), i.e. to emphasise that the Buddha "only a man" -- though for some people "teacher" is implicitly an honorific too.

There are many/various honorifics available in English:

• "lord" (religious and secular)
• "sir" (secular and military)
• "excellency" (bishops and heads of state)
• "holiness" (supreme religious leaders: the pope, orthodox patriarchs, the dalai lama)

To some extent none of these are exact translations: because their "meaning" derives from the context in which they're used, and in English they're used to refer to people other than the Buddha.

To some extent any of them are more-or-less adequate translations -- they mean more-or-less approximately the same thing, the difference being a difference in register -- "Lord" is a word from the frozen (static, literary) register:

Frozen: Also referred to as static register. Printed unchanging language, such as Biblical quotations, often contains archaisms.

"Sir" is more from the current (modern) register, although still formal and explicitly polite.

Because of the difficulty in translating -- i.e. most any Pali word can probably be translated by more than one English word, approximately but not exactly correct -- I begin to learn and recognise the Pali words. These Pali terms are then loanwords used as a specialized or technical vocabulary.

If you look at this translation of SN 56.11 for example it uses (quite of lot of) Pali words in its English translation, perhaps because there's no exact translation into English ...

On one occasion, the Bhagavā was staying at Varanasi in the Deer Grove at Isipatana. There, he addressed the group of five bhikkhus:

... but you can hover (with a mouse) or click on the links, to see a definition.

IMO these ('foreign') words then acquire meaning from the context in which you read them (and from the people who use them).

Some other characteristics, epithets, honorifics applied to the Buddha are listed here:

These characteristics are frequently mentioned in the Pāli Canon as well as Mahayana teachings, and are chanted daily in many Buddhist monasteries:

1. Thus gone, thus come (Skt: tathāgata)
2. Worthy one (Skt: arhat)
3. Perfectly self-enlightened (Skt: samyak-saṃbuddha)
4. Perfected in knowledge and conduct (Skt: vidyā-caraṇa-saṃpanna)
5. Well gone (Skt: sugata)
6. Knower of the world (Skt: lokavida)
7. Unsurpassed (Skt: anuttara)
8. Leader of persons to be tamed (Skt: puruṣa-damya-sārathi)
9. Teacher of the gods and humans (Skt: śāsta deva-manuṣyāṇaṃ)
10. The Blessed One or fortunate one (Skt: bhagavat)

The tenth epithet is sometimes listed as "The World Honored Enlightened One" (Skt. Buddha-Lokanatha) or "The Blessed Enlightened One" (Skt. Buddha-Bhagavan).

In ancient Pali and Sanskrit texts the most common title for the Buddha is Bhagavan, which means someone rich and/or important (like e.g. Bill Gates or the president etc). This is how the Buddha is often called in the third person (i.e. Bhagavan raised from his seat and said...)

The way the Buddha is usually addressed in the second person (i.e. when you say "yes, sir, I'll do as you say sir") - is "bhante". This is understood to be a Pali version of the Sanskrit "bhavantaḥ" which means "all of you" or "[plural] you" or "the big/important you".

Another common reference is Sugata, which means the lucky one or the successful one.

Finally sometimes he's called Jina which means the victor or the winner (in a battle).

Lord is a common English translation of the first title, Bhagavan, and sometimes of the second one, Bhante.