An auxiliary verb, also known as a helping verb, is used to provide additional information about the main verb in a sentence. The crossword solutions for the term 'auxiliary verb' are DOST (4 letters), MODAL (5 letters), AVOIR (5 letters), ARE (3 letters), DOTH (4 letters), DOES (4 letters), HAVE (4 letters), DID (3 letters), HAD (3 letters), LEMMA (5 letters), and WOULD (5 letters). These words are all examples of auxiliary verbs that can be used to provide more information about the main verb in a sentence.