suffix forming adjectives, esp. from nouns in -acea, -aceae (herbaceous; rosaceous).
Etymology: L -aceus: see -ACEA

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\\|āshəs\ adjective suffix
Etymology: Latin -aceus
: characterized by



: of the nature of


: belonging to or connected with a division of animals characterized by or of the nature of



: belonging to or connected with a family of plants of the nature of


— often in adjectives corresponding to biological classification names in -acea, -aceae

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a suffix with the meanings "resembling, having the nature of," "made of," occurring in loanwords from Latin (cretaceous; herbaceous) and forming adjectives in English on the Latin model (ceraceous), esp. adjectival correspondents to taxonomic names ending in -acea and -aceae: rosaceous.
[ < L -aceus; see -OUS]

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-aceous /-ā-shəs/
Relating or related to, resembling, etc

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adjective suffix. having the appearance of; of or like; containing, as in arenaceous, cretaceous, herbaceous, sebaceous. -aceous is used in botany as a termination of adjectives accompanying New Latin names ending in -aceae for various families of plants, as in liliaceous (New Latin Liliaceae, the lily family).
[< Latin -āceus]

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1) Botany forming adjectives from nouns ending in -aceae (such as ericaceous from Ericaceae)
2) chiefly Biology & Geology forming adjectives describing similarity, esp. in shape, texture, or color

arenaceous | foliaceous | olivaceous

from Latin -aceus, adjectival ending meaning ‘of the nature of’

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compd. adj. formative f. L. -āce-us, -a, -um, of the nature of, (f. āc- + -e-us, -e-a, -e-um, see -eous) + -ous, favoured by the formal resemblance of the compd. Eng. -ace-ous to the simple L. -āce-us of the nom. masc. Of extensive use in Nat. Hist., where it supplies adjectives, Eng. in form, to the nouns in -ācea, -āceae, as cetaceous, crustaceous, testaceous, rosaceous, ranunculaceous, papilionaceous; also in other words, as setaceous, cretaceous, carbonaceous, saponaceous, argillaceous, coriaceous, herbaceous, membranaceous, etc. Only a few of these represent actual L. words in -āceus, the majority being purely modern and analogical.

Useful english dictionary. 2012.