The meaning/concept of maññassavā / Dhatu-vibhanga Sutta (MN 140)

I guess:

• maññassavā = mañña/maññe + asavā

Then later in the explanation:

• maññitametaṃ = maññita + me + taṃ = imagination/conception/construction of me

Concise Pali English Dictionary

me

dat. and gen. sing. of amha to me;

my; mine.

PTS Pali English Dictionary

me is enclitic form of ahaṃ in var. cases of the sg. See under ahaṃ.

Another similar common word in the suttas is maññamāna.

This is explained by Piya Tan in his commentary on Dhatuvibhanga Sutta:

Maññassavāna-p,pavattanti, maññassave kho pana na-p,pavattamane. Here maññassavā is resolved as mañña (“conceiving”) + assava (Skt āsrava),(a) “purulent matter, discharge” (A 1:124); (b) tt for obstacle to arhathood, “canker, influx, inflow, taint” (V 3:21 = 5:143 = A 5:70, V 5:225, D 3:216, M 1:55, S 5:410, Sn 535, Thī 76); also related to āsava (spirituous liquor) because both are kept for a long time, MA 1:61 = AA 2:183 = ItA 1:114). The word assava is also related to assavati,“it flows (on)”). In this context, pavattanti should be rendered as “they flow” (S 2:31,J 2:104; PvA 143, 154, 198): M:ÑB reading maññ‟ussavā (wr for maññ‟ussāvā): “the tides of conceiving...sweep.”

Mental conceiving (mañña), closely related to “mental proliferation” (papañca), here refers to thoughts and ideas arising from the three roots of conceiving or mental proliferation: craving (taṇhā), view (diṭṭhi) and conceit (māna) (Nm 280; Vbh 393; Nett 37 f). For an interesting n on maññati, see M:ÑB 1162:n6. The “sage at peace” is the arhat.

The term asava is usually translated as effluents or taints or defilements. You can read the question "What is effluent?"

When reading the Dhatuvibhanga Sutta (translated by Ven. Sujato), we find some details for this:

‘They have four foundations, standing on which the streams of identification don’t flow. And when the streams of identification don’t flow, they’re called a sage at peace.’ That’s what I said, but why did I say it?

These are all forms of identifying: ‘I am’, ‘I am this’, ‘I will be’, ‘I will not be’, ‘I will have form’, ‘I will be formless’, ‘I will be percipient’, ‘I will be non-percipient’, ‘I will be neither percipient nor non-percipient.’ Identification is a disease, a boil, a dart. Having gone beyond all identification, one is called a sage at peace. The sage at peace is not reborn, does not grow old, and does not die. They are not shaken, and do not yearn. For they have nothing which would cause them to be reborn. Not being reborn, how could they grow old? Not growing old, how could they die? Not dying, how could they be shaken? Not shaking, for what could they yearn?

It sounds to me like maññassava is more or less the same as bhavāsava, the effluent or taint or defilement of becoming or being.

This can be found in MN 9 (translated by Ven. Bodhi):

“And what are the taints, what is the origin of the taints, what is the cessation of the taints, what is the way leading to the cessation of the taints? There are these three taints: the taint of sensual desire, the taint of being, and the taint of ignorance. With the arising of ignorance there is the arising of the taints. With the cessation of ignorance there is the cessation of the taints. The way leading to the cessation of the taints is just this Noble Eightfold Path; that is, right view, right intention, right speech, right action, right livelihood, right effort, right mindfulness, and right concentration.

And also AN 6.63 (translated by Ven. Thanissaro):

“There are these three kinds of defilements: the defilement of sensuality, the defilement of becoming, the defilement of ignorance.

“And what is the cause of defilements? Ignorance is the cause of defilements.

“And what is the diversity in defilements? There are defilements that lead to hell, those that lead to the animal womb, those that lead to the realm of the hungry shades, those that lead to the human world, those that lead to the world of the devas. This is called the diversity in defilements.

“And what is the result of defilements? One who is immersed in ignorance produces a corresponding state of existence, on the side of merit or demerit. This is called the result of defilements.

“And what is the cessation of defilements? From the cessation of ignorance is the cessation of defilements; and just this noble eightfold path—right view, right resolve, right speech, right action, right livelihood, right effort, right mindfulness, right samādhi—is the way leading to the cessation of defilements.