A Grammatical Dictionary of Botanical Latin

-unculus,-i (s.m.II),-a,-ae (s.f.I),-um,-i (s.n.II): noun suffix; associated with the Latin diminutive adjective or noun suffix -culus, -culus,-culum, but with the included syllable -un- preceding it; see -ulus,-i (s.m.II);

- icuncula,-ae (s.f.I), abl.sg. icuncula: a small icon , drawing, engraving, illustraton, plate or picture [> L. icon,-onis (s.f.III), abl. sg. icone, nom. & acc. pl. icones: drawing, engraving, illustration, plate + dim. –unculus,-a,-um (adj.A).

- homunculus,-i (s.m.II), a little man [> L. homo,-inis (s.m. III), a man]; pedunculus,-i (s.m.II), a little foot [>L. pes, gen.sg. pedis (s.m.III) foot]; ramunculus,-i (s.m.II), twig (little branch) [> Latin ramus,-i, (s.m.II) a branch]; pedunculus,-i (s.m.II), peduncle, 'little foot' [>L. pes, gen.sg. pedis (s.m.III) foot].

- Centunculus L. [> "Latin name of some plant, diminutive of cento,-onis (s.m.III) patchwork" (Fernald, 1950) p. 1143; Ranunculus,-i (s.m.II), a small frog] [> L. rana,-ae s.f.I, frog].

- capeduncula,-ae (s.f.I) a small bowl, etc. [> L. capedo,-inis (s.f.III) a bowl or cup used in sacrifices]; offensiuncula,-ae (s.f.I) a slight offense [>L. offensio,-onis (s.f.III)], quaestiuncula,-ae (s.f.I) a little or trifling question [> L. quaestio,-onis (s.f.III), a question]; stipulatiuncula,-ae (s.f.I) a little or minor promise [> L. stipulatio,-onis (s.f.III), a promise].

- apparently an adjective: Iguanura palmuncula, little palm.

NOTE: the adjective ending -ius- + -culus,-a,-um seems to be related, the -ius giving a greater degree of diminution than -culus; see -iusculus,-a,-um.