-ellus

By rebracketing of diminutives such as libellus (liber +‎ -lus) or fēmella (fēmina +‎ -la), where the stem consonants -n- and -r- shifted to -l- by regressive assimilation; or diminutives of diminutives such as porcellus (porculus +‎ -lus).

• (Classical) IPA^(key): /ˈel.lus/, [ˈɛlːʲʊs̠]
• (modern Italianate Ecclesiastical) IPA^(key): /ˈel.lus/, [ˈɛlːus]

-ellus (feminine -ella, neuter -ellum); first/second-declension suffix

1. Alternative form of -ulus

   ‎ager + ‎-ellus → ‎agrellus (“little field”) (compare this to agellus, which is from ager +‎ -lus)

The suffix -ellus is added to a noun to form a diminutive of that noun.

‎calamus (“reed”) + ‎-ellus → ‎calamellus (“little reed or pen”)

When added to an adjective, it forms a diminutive of that adjective.

‎hirtus (“hairy”) + ‎-ellus → ‎hirtellus (“slightly hairy”)

First/second-declension adjective.