The building blocks of English

Affixes

-aceous

Forming adjectives.

Latin adjectival ending ‑aceus, of the nature of, plus ‑ous.

Some examples are formed from plant family names in ‑aceae: rosaceous, of the rose family, the Rosaceae; orchidaceous, of an orchid, a member of the Orchidaceae family; solanaceous, of the Solanaceae, the nightshade family.

The ending also appears in a variety of words from biology and geology, as in herbaceous, relating to plants that are leafy and not woody; saponaceous (Latin sapon, soap), soapy ; olivaceous, having a dusky yellowish-green or olive-green colour; proteinaceous, of the nature of a protein or consisting of protein; and sebaceous (Latin sebum, tallow), resembling tallow or fat or secreting a fatty substance.

See also ‑ous.