Here you can look up the main prefixes which form Pali words and whose knowledge is sometimes required for understanding properly the original meaning.
abhi-:
1. towards, against to, on to, at-.
ex: gacchati: to go > abhi·gacchati: to go towards, approach
2. out, over, all around, on top of.
ex: jāti: birth > abhi·jāti: offspring
kamati: to affect, come to > abhi·kamati: exceed
tapati: to shine > abhi·tapati: to shine forth
3. transitivising intransitive verbs as does English be-.
ex: jāyati: to arise, be produced > abhi·jāyati: to beget
4. intensification: very much, greatly.
ex: nipuṇa: clever > abhi·nipuṇa: very clever
jighacchati: to be hungry > abhi·jighacchati: to be very hungry
vandati: to salute > abhi·vandati: to salute reverentially.
5. pleonastic: appears in double-prefix compounds where it is often seemingly superfluous, ie. weakened in meaning, when the second part already denotes intensity.
adhi-:
remark: before vowels becomes, ajjh-
ex: adhi+attaṃ= ajjh·attaṃ
1. toward, to, up to, on, over.
ex: gacchati: to go > adhi·gacchati: "to go on to & reach it" ie. obtain
gaṇhāti: to take, seize > adhi·gaṇhāti: to overtake, surpass
bhāsati: to speak > adhi·bhāsati: to speak to, address
2. where, here, on top of, above, over.
ex: ("where":) vasati: to live, dwell > adhi·vasati: to inhabit
("here":) atta: self > ajjh·atta: "this self here", personal, subjective, interior, inwardly
3. in addition, quite, very, super, higher.
ex: jeguccha: detestable > adhi·jeguccha: very detestable
paññā: wisdom > adhi·paññā: higher, additional wisdom.
anu-:
1. after, behind (motion viewed from the front backward).
ex: dhāvati: to run > anu·dhāvati: to run after
bala: military force > anu·bala: rearguard
bhāsati: to speak > anu·bhāsati: to speak after, repeat
2. for, towards an aim, on to, into, over to, forward (motion viewed from the back forward).
ex: pavecchati: to give, bestow > anu·pavecchati: to hand over
rodati: to cry, weep > anu·rodati: to cry for
pavisati: to enter > anu·pavisati: to enter into
3. (emphasis).
ex: dayā: sympathy, kindness > anu·ddayā: pity
yoga: application, endeavour > anu·yoga: devotion, dedication
vitakketi: to consider, reflect > anu·vitakketi: to ponder over
4. according to, in conformity with, along.
ex: ñāta: kown, well-knwon > anu·ñāta: permitted, allowed
mati: opinion > anu·mati: consent, agreement
rūpa: form > anu·rūpa: conform
anu·dhamma: in conformity with the dhamma
karoti: to do > anu·karoti: to imitate
5. secondary, supplementary, inferior, minor, smaller.
ex: pabbajā: ascetic life > anu·pabbajā: discipleship in ascetism
majjha: average > anu·majjha: mediocre
pavatteti: to set in motion > anu·pavatteti: to keep in motion
6. each, every, one by one.
ex: disā: direction > anu·disā: each direction
pubba: previous, former > anu·pubba: 'each after the previous one' ie. gradual
pañcāha: five days > anu·pañcāha: every five days.
paṭi-:
remark: also spelt pati-; before vowels becomes, pacc-
ex: paṭi+attaṃ= pacc·attaṃ
1. back, away from.
ex: patha: path, way > paṭi·patha: the opposite way.
kamati: to step > paṭi·kkamati: to step back, to retreat.
āneti: to bring > paṭi·āneti: to bring back.
2. against in opposition, contrary.
ex: karoti: to do, make > paṭi·karoti: to redress, repair, act against, be cautious.
manteti: to consult, take counsel > paṭi·manteti: to discuss in argument, refute.
remark: In this sense, opposed to anu-.
ex: sota: stream > anu·sota: with the stream; paṭi·sota: against the stream.
3. in return, in exchange (in revenge).
ex: bhāsati: to speak > paṭi·bhāsati: to speak back, to reply.
bhaṇḍa: goods, merchandise > paṭi·bhaṇḍa: merchandise in exchange, barter.
māreti: to kill > paṭi·māreti: to kill in revenge.
4. to, on to, up to, towards, at.
ex: jānāti: to know > paṭi·jānāti: to acknowledge, agree to, approve of.
5. again, a second time (Eng. re-).
ex: dasseti: to show, exhibit > paṭi·dasseti: to show up again, reappear.
nijjhatta: pacified > paṭi·nijjhatta: re-pacified.
sandhi: union > paṭi·sandhi: reunion (with a body), reincarnation.
6. secondary, minor.
ex: aṅga: limb > paṭi·aṅga: minor limb.
7. comparison.
ex: puggala: person > paṭi·puggala: rival, compeer.
8. sham.
ex: nāsikā: nose > paṭi·nāsikā: false nose.
sīsaka: top knot > paṭi·sīsaka: sham top knot.
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saṃ- (or sam-):
1. conjunction, closer connection = with, along, together.
ex: yutta: yoked, connected > saṃyutta: bound together, grouped.
vasati: to live > saṃvasati: to live together with
2. completeness, or accentuation of the meaning = thoroughly, quite, fully, perfectly. It often equals pa- with which it gets combined in sampa-.
ex: bodhi: awakening > sambodhi: complete awakening
jāna: knowing > sampajāna: knowing thoroughly.
3. pleonastic, without really modifying the meaning.
ex: bojjhaṅga: factor of awakening > sambojjhaṅga: factor of awakening.