The Collaborative International Dictionary
Ambigu \Am"bi*gu\, n. [F., fr. ambigu doubtful, L. ambiquus. See Ambiguous.] An entertainment at which a medley of dishes is set on at the same time.
n. (context dated English) An entertainment at which a medley of dishes is set on at the same time; a buffet.
Ambigu is a French term that was adopted to mean 'a mixture of things' relating to a type of meal that was popular amongst the English upper class during the mid-17th and mid-18th centuries. It was an evening meal that was less formal than dinner but still planned with a set table and varied types of cold food at the sideboard.