Both Uses

ambiguous
in
Looking for Alaska
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And I vaguely remember Lara smiling at me from the doorway, the glittering ambiguity of a girl's smile, which seems to promise an answer to the question but never gives it.†
p. 64.9 *

ambiguity = lack of clarity -- unclear because there could be two or more interpretations
I didn't know who "everyone" was, or when "always" was, and as much as I wanted to understand her ambiguities, the slyness was growing annoying.†
p. 95.4

ambiguities = things that are unclear -- because open to two or more interpretations

Definitions:

(1) (ambiguous)
unclear -- because there could be two or more interpretations
(2) (meaning too rare to warrant focus)
More rarely, ambiguous can mean uncertain or doubtful -- as in the expression "an ambiguous smile".