sleeve
Pronunciation: /sliːv/
noun
- 1the part of a garment that wholly or partly covers a person’s arm: a shirt with the sleeves rolled up

Phrases
-
up one's sleeve
- (of a strategy, idea, or resource) kept secret and in reserve for use when needed: he was new to the game but had a few tricks up his sleeve
-
wear one's heart on one's sleeve
- see heart.

Origin:
Old English slēfe, slīef(e), slȳf; related to Middle Dutch sloove 'covering'