An adjective phrase can be formed by combining an adverb functioning as an intensifier and an adjective. The dazzlingly beautiful woman walked down the street. (" dazzlingly" is an adverb and "beautiful" is an adjective) That lemon was amazingly sour. (" amazingly" is an adverb and "sour" is an adjective)
An adjective phrase is a phrase the head of which is an adjective, almost any grammar or syntax textbook or dictionary of linguistics terminology defines the adjective phrase in a similar way, e.g. Kesner Bland, Crystal, Greenbaum, Haegeman and Guéron, Brinton, Jurafsky and Martin
