Green’s Dictionary of Slang

1. (US) effeminate, homosexual.

1944		P. Kendall Dict. Service Sl. n.p.: he’s a bit lacy . . . girlish.
1972		R.A. Wilson Playboy’s Book of Forbidden Words.
2002		(con. WWII) R. Mooney Father of the Man Prologue: Weaver, a scrawny kid from Rhode Island, weakest guy in the platoon, last in everything, a bit lacy – if you know what I mean.

2. sexy.

1959

W. Brown Teen-Age Mafia 38: Whitey and that lacy trim of his were back in the section they’d boxed off with [...] curtains.