The Collaborative International Dictionary
Acorn cup \A"corn cup\ The involucre or cup in which the acorn is fixed.
Wiktionary
n. The involucre or cup in which the acorn is fixed.
WordNet
n. cup-shaped structure of hardened bracts at the base of an acorn [syn: cupule]
Usage examples of "acorn cup".
Meanwhile Random was trying to fend off the squirrel with the acorn cup full of rain and the one with the paper.
Then one darted straight at her, dropped the acorn cup in her lap, turned and ran off into the night.
Half an hour before dawn the young mouse was roused by a shrew who gave him an acorn cup full of sweet berry juice, a loaf of rough nutbread and some tasty fresh roots that he could not identify.
Your Uncle Hendreary never drank a thing that wasn't out of a common acorn cup, and he's lived to a ripe old age and had the strength to emigrate.
Stooping she picked from the grass beside her a fallen acorn cup and handed it to him.