Green’s Dictionary of Slang

1. to evade, to equivocate.

1900		Century Mag. (NY) June 305/2: I’ve seen him take his pen, and go through a proposed plank or resolution, and weasel every flat-footed word in it .
1948		Salt Lake Trib. 17 Dec. 3/3: Let’s not weasel-word. Let’s say just what we mean [DA].
1956		E. Pound trans. Sophocles’ Women of Trachis 20: By the black vale of Otea, don’t weasel me.
1999		Guardian Guide 26 June–2 July 89: Larry weasels out, then in, then out again of an invitation to a ball game.

2. to wriggle out of a promise or duty.

1948		Sat. Eve. Post 2 Oct. 40/3: Now, don’t try to weasel out of it [DA].
1989		H. Rawson Dict. of Invective (1991) 411: weasel. A sneaky fellow; one who weasels out of obligations.