Full Assimilation

Full assimilation in Hungarian is categorized into two main types: marked (where spelling changes) and unmarked (where only pronunciation changes).

A. Marked Full Assimilation (Spelling Changes)
1. The 'v' Suffixes:
The suffixes -val/-vel (with) and -vá/-vé (become) start with a 'v'. If the word they attach to ends in a consonant, the 'v' disappears and the stem's final consonant is doubled.
Example: láb + val = lábbal.
Note: If the word ends in a vowel, the 'v' remains (e.g., hajóval).

2. Demonstrative Pronouns:
When ez (this) or az (that) are followed by a case suffix starting with a consonant, the final 'z' of the pronoun usually assimilates to that consonant (e.g., ez + ben = ebben). When combined with -val/-vel, assimilation can go in either direction, but ezzel and azzal are the most common forms. Important Exceptions: The accusative suffix -t does not trigger assimilation; the forms remain ezt and azt. Additionally, the forms eddig and addig (with the terminative suffix -ig) are irregular historical stem changes of the demonstrative pronouns, rather than suffix-triggered assimilation.

3. Verb Stem Assimilation:
The suffix '-j' assimilates to stems ending in sibilants (s, sz, z, zs) and 'dz'. This occurs in the imperative/subjunctive mood (e.g., mos + jon = mosson, edz + j = eddz) and the definite conjugation of the present tense for these stems (e.g., olvas + ja = olvassa).

B. Unmarked Full Assimilation (Pronunciation Only)
In these cases, the spelling remains unchanged, but a consonant is fully assimilated in speech.
1. The '-j' Suffix: When '-j' follows gy, ny, or ty, the 'j' fully assimilates to the preceding consonant in pronunciation (e.g., hagyja is pronounced [haggya], and anyja is pronounced [annya]). However, when '-j' follows l, the 'l' assimilates to the 'j' (e.g., tanulja is pronounced [tanujja]).
2. Sibilant Combinations: Certain consonant clusters involving sibilants result in full assimilation in speech. Specifically, sz or z followed by s becomes a long [ss] (e.g., egészség is pronounced [egésség]), and s or z followed by sz becomes a long [ssz] (e.g., kisszoba is pronounced [kisszoba]).

Special Case: The 'h' Exception
In words like ehhez or ahhoz, the 'z' assimilates to 'h' in writing (hh), but it is typically pronounced as a single short [h] sound.

Note: Full Assimilation vs. Coalescence
It is important to distinguish unmarked full assimilation from coalescence (összeolvadás). In full assimilation, one consonant becomes identical to the other. In coalescence, two different consonants merge to form a completely new, third sound (e.g., t + j = ty, so látja is pronounced [láttya]).