-lus

From syncope of Proto-Italic *-elos (source of Classical Latin -ulus),[1] from Proto-Indo-European *-elós, thematized from *-lós.[2]

• (Classical) IPA^(key): /lus/, [ɫ̪ʊs̠]
• (Ecclesiastical) IPA^(key): /lus/, [lus]

-lus (feminine -la, neuter -lum); first/second-declension suffix

1. Alternative form of -ulus

The suffix -lus is added to a noun to form a diminutive of that noun. As with other Latin diminutive suffixes, the gender of the diminutive regularly matches the gender of the base noun.

This form of the diminutive suffix is used mainly on first-declension or second-declension nouns (sometimes adjectives) with stems ending in -ra-, -na-, -la- or -ro-, -no-, -lo- (corresponding to the nominative singular endings -ra, -na, -la; -er/-rus, -nus, -lus; or -rum, -num, -lum, depending on declension and gender).

As the result of syncope, the /r/, /n/, or /l/ of the stem is brought into contact with the /l/ of the diminutive suffix and is assimilated to it, forming geminate /ll/. If the /r/, /n/, or /l/ in the base word is preceded by a short vowel or consonant, then the /ll/ in the diminutive is preceded by short /e/ or short /i/, resulting in a form ending in -ellus (-a, -um) or -illus (-a, -um). The vowel used in the diminutive may differ from the vowel used in the base word. In the oldest formations, these vowels likely developed from regular sound changes. However, it is likely that many diminutives ending in -ellus and -illus were formed more recently than the stage when these sound changes occurred and took their vowels based on analogy with existing pairs of words. Thus, the endings -ellus and -illus had already started to be extended as suffixes in their own right in pre-literary times.

However, if for the sake of morphological analysis we treat diminutives formed from bases in -ra-/-ro-, -na-/-no-, or -la-/-lo- as ending in the suffix -lus, the following generalizations can be made about their vocalism:

Bases with stems ending in -ra-/-ro- preceded by either the short vowel /e/ or by another consonant form their diminutives with /ell/ (per Strodach, the only exception attested in Republican Latin is trānstillum from trānstrum; a second exception attested in Imperial Latin is verētillum/verētilla from verētrum):

‎liber (“book”) + ‎-lus → ‎libellus (“booklet”)

‎opera (“work”) + ‎-lus → ‎opella (“light work”)

‎cerebrum (“brain”) + ‎-lus → ‎cerebellum (“a small brain”)

Bases with stems ending in -na-/-no- preceded by a long vowel retain the quality and probably also the quantity of the long vowel before the geminate /ll/:

‎catēna (“chain”) + ‎-lus → ‎catēlla (“a little/ornamental chain”)

‎vīnum (“wine”) + ‎-lus → ‎vīllum (“a little wine”)

‎corōna (“garland, wreath, crown”) + ‎-lus → ‎corōlla (“little crown, garland”)

Bases with stems ending in -na-/-no- preceded by another consonant form their diminutives most often with /ill/, sometimes with /ell/:

‎signum (“sign, mark, statue”) + ‎-lus → ‎sigillum (“seal, statuette”)

Bases with stems ending in -na-/-no- preceded by the short vowel /i/ form their diminutives with /ell/ (with the exception of māchilla from māchina[3]). This /i/-/e/ alternation likely developed initially from the sound change of vowel reduction, by which original short vowels /e/ or /a/ regularly turned into /i/ in word-medial open syllables but into /e/ in word-medial closed syllables:

‎asinus (“ass, donkey”) + ‎-lus → ‎asellus (“small (or young) ass, donkey”)

‎fēmina (“woman, female”) + ‎-lus → ‎fēmella (“girl, young woman”)

Bases with stems ending in -la-/-lo- preceded by the short vowel /u/ sometimes form their diminutives with /ell/ and sometimes in /ill/:

‎oculus (“eye”) + ‎-lus → ‎ocellus (“little eye”)

‎ancula (“maidservant”) + ‎-lus → ‎ancilla (“maid, slave girl”)

‎porcus (“pig”) + ‎-lus → ‎porculus (“young pig, little pig, piglet”), ‎porculus + ‎-lus → ‎porcellus (“little pig, piglet”)

In some words, the base but not the diminutive shows the effect of sound changes on consonant clusters:

‎scamnum (“stool”) + ‎-lus → ‎scabillum (“footstool”) (base originally had -bn-, which turned into -mn- by regressive assimilation to nasality)

‎vannus (“winnowing basket”) + ‎-lus → ‎vatillum (“shovel”) (base originally had -tn-, which turned into -nn- by regressive assimilation to nasality)

‎māla (“cheekbone, jaw”) + ‎-lus → ‎maxilla (“jawbone”) (base originally had -ksl-, which turned into -◌̄l- by lenition of s-final clusters before voiced consonants)

A few third-declension nouns with stems ending in -r- or -n- may form diminutives with -lus:

Examples:

‎homō (“man (human being)”) + ‎-lus → ‎homullus (“little man”)

‎frāter (“brother”) + ‎-lus → ‎frātellus (“brother”)

First/second-declension adjective.

• -ellus
• -illus
• -ullus