Ambiguous, a.
Etymology: [L. ambiguus, fr. ambigere to wander about, waver; amb- + agere to drive.]
Doubtful or uncertain, particularly in respect to signification; capable of being understood in either of two or more possible senses; equivocal; as, an ambiguous course; an ambiguous expression. What have been thy answers What but dark, Ambiguous, and with double sense deluding Milton.
Syn. -- Doubtful; dubious; uncertain; unsettled; indistinct; indeterminate; indefinite. See Equivocal.
Shades of meaning
Fernald has no entry of its own for ambiguous; he lists it under equivocal, obscure.
Where he writes about it:
Ambiguous (L. ambi, around, and ago, drive, lead) signifies lacking in distinctness or certainty, obscure or doubtful through indefiniteness of expression. — from equivocal
Ambiguous is applied only to spoken or written statements; equivocal has other applications. — from equivocal
A statement is ambiguous when it leaves the mind of the reader or hearer to fluctuate between two meanings, which would fit the language equally well; it is equivocal when it would naturally be understood in one way, but is capable of a different interpretation; an equivocal expression is, as a rule, intentionally deceptive, while an ambiguous utterance may be simply the result of a want either of clear thought or of adequate expression. — from equivocal