备用大锚, 最后的希望, 最后的手段

[ noun ]
spare anchor for use in emergency
<noun.artifact>

Sheet anchor \Sheet" an"chor\ [OE. scheten to shoot, AS.
sce['o]tan; cf. OE. shoot anchor. See {Shoot}, v. t.]
1. (Naut.) A large anchor stowed on shores outside the waist
of a vessel; -- called also {waist anchor}. See the Note
under {Anchor}.

2. Anything regarded as a sure support or dependence in
danger; the best hope or refuge.