A New Dictionary

Ambiguous
-adjective

1. open to or having several possible meanings or interpretations; equivocal: an ambiguous answer.
2. Linguistics. (of an expression) exhibiting constructional homonymity; having two or more structural descriptions, as the sequence Flying planes can be dangerous.
3. of doubtful or uncertain nature; difficult to comprehend, distinguish, or classify: a person of ambiguous character.

The word ambiguous is derived from the Latin ambiguus "having double meaning, shifting, doubtful," which in turn comes from ambigere "to dispute about," literally "to wander" from ambi- "about" and agere "drive, lead".
Sir Thomas More seems to have first used it in English in 1528, but ambiguity (from Latin ambiguitatem) is first recorded circa 1400.

The post title of doppeldeutig is not ambiguous. Well, actually it is. That is the German word for ambiguous. And there is no ambiguity surrounding that fact.