Both Uses of

equivocal
in
The Fall of the House of Usher

I learned, moreover, at intervals, and through broken and equivocal hints, another singular feature of his mental condition.
*

equivocal = unclear in meaning

It was this deficiency, I considered, while running over in thought the perfect keeping of the character of the premises with the accredited character of the people, and while speculating upon the possible influence which the one, in the long lapse of centuries, might have exercised upon the other—it was this deficiency, perhaps, of collateral issue, and the consequent undeviating transmission, from sire to son, of the patrimony with the name, which had, at length, so identified the two as to merge the original title of the estate in the quaint and equivocal appellation of the "House of Usher"—an appellation which seemed to include, in the minds of the peasantry who used it, both the family†

Definitions:

(1) (equivocal)
unclear in meaning -- especially where opposing interpretations are reasonable (sometimes intentionally)
(2) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

The form unequivocal (not equivocal; or clean in meaning) is encountered much more frequently, but equivocal is seen on many more SAT review lists.