ភាសាបាលី: Assimilations

Assimilations 
 ក្បួនច្បាប់ទូទៅ 
Many assimilations of one consonant to a neighboring consonant occurred in the development of Pali, producing a large number of geminate (double) consonants. Since aspiration of a geminate consonant is only phonetically detectable on the last consonant of a cluster, geminate kh, gh, ch, jh, ṭh, ḍh, th, dh, ph and bh appear as kkh, ggh, cch, jjh, ṭṭh, ḍḍh, tth, ddh, pph and bbh, not as khkh, ghgh etc.
When assimilation would produce a geminate consonant (or a sequence of unaspirated stop+aspirated stop) at the beginning of a word, the initial geminate is simplified to a single consonant.
Examples: prāṇa → pāṇa (not ppāṇa), sthavira → thera (not tthera), dhyāna → jhāna (not jjhāna), jñāti → ñāti (not ññāti)
When assimilation would produce a sequence of three consonants in the middle of a word, geminates are simplified until there are only two consonants in sequence.
Examples: uttrāsa → uttāsa (not utttāsa), mantra → manta (not mantta), indra → inda (not indda), vandhya → vañjha (not vañjjha)
The sequence vv resulting from assimilation changes to bb
Example: sarva → savva → sabba, pravrajati → pavvajati → pabbajati, divya → divva → dibba

 Total assimilation 
Total assimilation, where one sound becomes identical to a neighboring sound, is of two types: progressive, where the assimilated sound becomes identical to the following sound; and regressive, where it becomes identical to the preceding sound.

 Progressive assimilations 
Internal visarga assimilates to a following voiceless stop or sibilant
Examples: duḥkṛta → dukkata, duḥkha → dukkha, duḥprajña → duppañña, niḥkrodha (=niṣkrodha) → nikkodha, niḥpakva (=niṣpakva) → nippakka, niḥśoka → nissoka, niḥsattva → nissatta
In a sequence of two dissimilar Sanskrit stops, the first stop assimilates to the second stop
Examples: vimukti → vimutti, dugdha → duddha, utpāda → uppāda, pudgala → puggala, udghoṣa → ugghosa, adbhuta → abbhuta, śabda → sadda
In a sequence of two dissimilar nasals, the first nasal assimilates to the second nasal
Example: unmatta → ummatta, pradyumna → pajjunna
j assimilates to a following ñ (i.e., jñ becomes ññ)
Examples: prajñā → paññā, jñāti → ñāti
The Sanskrit liquid consonants r and l assimilate to a following stop, nasal, sibilant, or v
Examples: mārga → magga, karma → kamma, varṣa → vassa, kalpa → kappa, sarva → savva → sabba
r assimilates to a following l
Examples: durlabha → dullabha, nirlopa → nillopa
d sometimes assimilates to a following v, producing vv → bb
Examples: udvigna → uvvigga → ubbigga, dvādaśa → bārasa (beside dvādasa)
t and d may assimilate to a following s or y when a morpheme boundary intervenes
Examples: ut+sava → ussava, ud+yāna → uyyāna

 Regressive assimilations 
Nasals sometimes assimilate to a preceding stop (in other cases epenthesis occurs; see below)
Examples: agni → aggi, ātman → atta, prāpnoti → pappoti, śaknoti → sakkoti
m assimilates to an initial sibilant
Examples: smarati → sarati, smṛti → sati
Nasals assimilate to a preceding stop+sibilant cluster, which then develops in the same way as such clusters without following nasals (see Partial assimilations below)
Examples: tīkṣṇa → tikṣa → tikkha, lakṣmī → lakṣī →lakkhī
The Sanskrit liquid consonants r and l assimilate to a preceding stop, nasal, sibilant, or v
Examples: prāṇa → pāṇa, grāma → gāma,  śrāvaka → sāvaka, agra → agga, indra → inda, pravrajati → pavvajati → pabbajati, aśru → assu
y assimilates to preceding non-dental/retroflex stops or nasals
Examples: cyavati → cavati, jyotiṣ → joti, rājya → rajja, matsya → macchya → maccha, lapsyate → lacchyate → lacchati, abhyāgata → abbhāgata, ākhyāti → akkhāti, saṁkhyā → saṅkhā (but also saṅkhyā), ramya → ramma
y assimilates to preceding non-initial v, producing vv → bb
Example: divya → divva → dibba, veditavya → veditavva → veditabba, bhāvya → bhavva → bhabba
y and v assimilate to any preceding sibilant, producing ss
Examples: paśyati → passati, śyena → sena, aśva → assa, īśvara → issara, kariṣyati → karissati, tasya → tassa, svāmin → sāmī
v sometimes assimilates to a preceding stop
Examples: pakva → pakka, catvāri → cattāri, sattva → satta, dhvaja → dhaja

 Partial and mutual assimilation 
Sanskrit sibilants before a stop assimilate to that stop, and if that stop is not already aspirated, it becomes aspirated; e.g. śc, st,  ṣṭ and sp become cch, tth, ṭṭh and pph
Examples: paścāt → pacchā, asti → atthi, stava → thava, śreṣṭha → seṭṭha, aṣṭa → aṭṭha, sparśa → phassa
In sibilant-stop-liquid sequences, the liquid is assimilated to the preceding consonant, and the cluster behaves like sibilant-stop sequences; e.g. str and ṣṭr become tth and ṭṭh
Examples: śāstra → śasta → sattha, rāṣṭra → raṣṭa → raṭṭha
t and p become c before s, and the sibilant assimilates to the preceding sound as an aspirate (i.e., the sequences ts and ps become cch)
Examples: vatsa → vaccha, apsaras → accharā
A sibilant assimilates to a preceding k as an aspirate (i.e., the sequence kṣ becomes kkh)
Examples: bhikṣu → bhikkhu, kṣānti → khanti
Any dental or retroflex stop or nasal followed by y converts to the corresponding palatal sound, and the y assimilates to this new consonant, i.e. ty, thy, dy, dhy, ny become cc, cch, jj, jjh, ññ; likewise ṇy becomes ññ.  Nasals preceding a stop that becomes palatal share this change.
Examples: tyajati → cyajati → cajati, satya → sacya → sacca, mithyā →  michyā → micchā, vidyā → vijyā →  vijjā, madhya → majhya → majjha, anya → añya → añña, puṇya → puñya → puñña, vandhya →  vañjhya → vañjjha → vañjha
The sequence mr becomes mb, via the epenthesis of a stop between the nasal and liquid, followed by assimilation of the liquid to the stop and subsequent simplification of the resulting geminate.
Examples: āmra → ambra → amba, tāmra → tamba