Linking Vowels

In Hungarian, when a suffix starting with a consonant (like -k or -t) is added to a noun ending in a consonant, a linking vowel is often needed. Conversely, nouns already ending in a vowel generally do not take linking vowels at all (e.g., kocsi → kocsik, kocsit), though stem-final a and e lengthen to á and é (e.g., alma → almák) due to stem-final vowel lengthening. Exceptions include certain vowel-ending stems that drop their final vowel and take a linking vowel (e.g., borjú → borjak, and fiú → fiak when meaning 'sons', whereas 'boys' is the regular fiúk), as well as v-inserting stems, which mutate to end in a consonant before taking a linking vowel (e.g., ló → lovak).

1. Regular Stems (Mid-Vowel):
Most nouns follow vowel harmony using mid-vowels: o (back), e (front-unrounded), or ö (front-rounded).
Example: asztal (table) → asztalok.

2. Lowering Stems (Low-Vowel):
A specific set of nouns (nyitótő) and adjectives require low-vowels. For adjectives ending in a consonant, low vowels are the standard default, though there are significant and common lexical exceptions that take mid-vowels (e.g., nagyok, boldogok, gazdagok). Furthermore, when an adjective is used as a noun (substantivization), it reverts to standard noun declension using mid-vowels. For example, okosak means 'smart' (adjective), while okosok means 'smart people' (noun). These lowering stems still strictly obey vowel harmony rules: a (back) or e (front). Note that for front-unrounded stems, the distinction is invisible for many suffixes (like the plural) because e serves as both the mid and low vowel, though it can become visible in the accusative case (as explained in Section 3). However, front-rounded lowering stems use e instead of ö.
Examples of back-vowel lowering stems: ház (house) → házak; piros (red) → pirosak. Example of a front-rounded lowering stem: föld (earth) → földek. Some vowel-dropping stems (e.g., ajak → ajkak), vowel-shortening stems (e.g., madár → madarak), and v-inserting stems (e.g., ló → lovak) also follow this lowering pattern.

3. The Accusative Exception:
For nouns, regular stems ending in a single 'easy' consonant (j, l, ly, n, ny, r, s, sz, z, zs) usually drop the linking vowel in the accusative case (e.g., dalt). However, this vowel-dropping rule generally applies to nouns; most adjectives ending in these exact same consonants require a linking vowel (e.g., kész → készet, magas → magasat), though adjectives with privative suffixes (e.g., ismeretlen → ismeretlent) and nationalities (e.g., lengyel → lengyelt) drop the vowel. Stems ending in a consonant cluster or a long consonant usually require a linking vowel (e.g., vers → verset, könny → könnyet), though there are exceptions (e.g., pénz → pénzt). Furthermore, lowering stems ending in a consonant never drop it (e.g., halat). For front-unrounded stems ending in these consonants, the accusative case reveals whether they are regular (dropping the vowel, e.g., vér → vért) or lowering (keeping the vowel, e.g., szél → szelet). Note that for front-unrounded stems ending in 'hard' consonants (like p or k), the regular vs. lowering distinction is completely invisible even in the accusative case (e.g., regular kép and lowering szép both take e: képet, szépet). Additionally, when a back-vowel noun has a possessive suffix, its accusative linking vowel is always a, overriding the mid-vowel default (e.g., házam + t = házamat).

4. Suffix Specificity:
Lowering affects certain suffixes, such as the plural, the accusative, and the 1st/2nd person singular and 2nd person plural possessive suffixes (e.g., házam, házad, házatok). It also affects other suffixes like the distributive (-nként), the sociative (-stul/-stül), and certain derivational suffixes like the adjective-forming -s. Lowering stems also typically favor the -a/-e version of the 3rd person possessive over -ja/-je (e.g., háza). Note that here, -a/-e is the actual suffix itself, not a linking vowel plus a consonant, and there are exceptions (e.g., hold is a lowering stem but takes -ja: holdja). Lowering does not affect the 1st and 3rd person plural possessive (-unk/-ünk, -uk/-ük), which use high vowels, or the superessive case (-on/-en/-ön), which always uses mid-vowels.