What’s not to like about a word that has twelve letters, nine phonemes, four syllables, one spot where there are three consonants together and another where there are three vowels together, and two instances of ac?
Its first consonant is that hard back [k], but then, after landing on a pillow of a tongue-tip [n], it does the three voiceless fricatives that use the front of the tongue: [θ], [ʃ], and [s]. Soft and fresh like a spring shower. When you look at the word, you see the words can, cant, ant, nth, ace, and us. But in the main it just looks like a heap of curly foliage with a couple of spiky bits sticking up.
So what is it? It’s what you always wanted but never knew it: it’s an adjective referring to being like an acanthus.
And what is an acanthus? It’s a thorny plant with spiky-shaped leaves (rather like big dandelion or thistle leaves, really). Its leaves are featured curling at the tops of Corinthian columns.
The word acanthus is a Latinization of the Greek ἄκανθος, which may come from an ἄκ- root for pointy things (such as acupuncture needles) plus an ἄνθος root for flowers. So pointy (thorny) flower. And then that Greek assemblage gets a Latin-derived adjectival suffix and we have acanthaceous. You are at this very moment probably thinking about a coelacanth eating a herbaceous anthurium. Rest assured that the roots of those words are just as they look.
And where will you use acanthaceous? When describing the tops of Corinthian columns, perhaps, or some foliage sprouting from a sidewalk crack. Or someone’s hair. Apparently styles like that are a thing again.