Definitions for "Auxiliary verb"
Keywords:  tense, verb, modal, mood, voice
a conjugated verb used in front of another verb in compound tenses in order to help form the mood and tense of the verb
a helping verb used to express tense , mood , or voice
a verb that accompanies the main verb in a clause and helps to make distinctions in mood, voice, aspect, or tense
Keywords:  catenative, operator
a catenative which is also an operator