-aceous, -acea, -aceae, -aceaen, -aceus

(Latin: a suffix; having the quality of, of the nature of, characterized by, belonging to, resembling)

There are hunderds of words that utilize the -aceous suffix which are not shown here; however, the following will present important examples.

A suffix that forms adjectives and is used with technical combinations, especially in biological terms: "pertaining or belonging to, of the nature of, or characterized by; to be full of, to possess abundantly". The suffix -acea usually denotes "orders and classes in zoology" while the suffix -aceae usually denotes "orders and families in botany" and -aceaen is used to denote members of "orders of the animal kingdom".

saponaceous (adjective), more saponaceous, most saponaceous
1. Of the nature of, or resembling, soap; consisting of, or containing, soap; soapy: The saponaceous bar he used in the shower was of medium size and smooth like silk.
2. Used figuratively: slippery; evasive: Jack's reasons were very saporaceous and he avoided telling his parents the real truth.
saxifragaceous (adjective) (not comparable)
Pertaining to the order of Saxifragaceæ: The gooseberry and the hydrangea belong to the group of saxifragaceous plants.
Schistostegaceae (proper noun)
The family of luminous moss: The mosses of the Schistostegaceae family comprise those of shining or illuminated mosses that have lens-like cells that make them gleam or radiate like cats' eyes.
sebaceous (adjective) (not countable)
1. Pertaining to, of the nature of, or resembling tallow or fat; oily, greasy: The French fries were so sebaceous that Susan had to use a napkin to wipe her fingers each time she ate one!
2. Containing, or pertaining to, sebum, the oily secretion of a cutaneous gland: The sebaceous glands in men are larger than in women, and therefore perhaps explains why men have more problems with dandruff that women.
semiherbaceous (adjective), more semiherbaceous, most semiherbaceous
Referring to a plant being woody as well as nonwoody: Herbaceous plants are those that produce wood as its main structural tissue with hard stems, while the semiherbaceous ones have both a woody structure as well as green bending stems.
setaceous (adjective), more setaceous, most setaceous
1. Having or covered with protective barbs, quills, thorns, or setae, etc.: Lots of cacti are setaceous having spines covering the whole plant.
2. Resembling bristles or a bristle: So many men these days appear with setaceous whiskers.
siphonaceous (adjective) (not comparable)
Relating to the order Siphonales: The characteristic of being siphonaceous is applied to the grass-green or florideous algae which possess siphons.
suprafoliaceous (adjective) (nor comparable)
Relating to a peduncle or flower which was inserted into the stem of a plant: The suprafoliaceous flower that Jane observed was just above the axil of the stem on her rose bush.
terraceous (adjective), more terraceous, most terraceous
Earthen or of the earth. earthy: The jug Sam was using was from his neighbour who said it was made of a terraceous clay.
ulotrichaceous (adjective) (not comparable)
A reference to the family of Ulotrichaceae: The algae pictured in Jane's biology book were described as being ulotrichaceous, or illustrated as being the green algae.
vinaceous (adjective), more vinaceous, most vinaceous
Relating to the reddish color of wine; wine-colored: The grape juice Jack ordered at the restaurant was of a vinaceous hue or shade.
Vitaceae (proper noun)
A family of vines included in the in the order Rhamnales: The Vitaceae comprise the dicotyledonous plants which are mostly tendril-bearing climbers with compound or lobed leaves, as in grapes and the Virginia creeper.
zygnemaceous (adjective) (not comparable)
Concerning the family of Zygnemaceæ: The zygnemaceous algae are also included in the genus of Zygnema.
zygophyllaceous (adjective) (not comparable)
Regarding flowering plants that have pinnate leaves (a central stem with parts branching off it like feathers) and capsules as fruits: Jane had some zygophyllaceous shrubs in her garden, like bean-capers and caltrops.

Also see this closely related -eous suffix unit.