zero infinitive

A type of complement with an infinitive verb form that is not preceded by the particle to. Also known as the bare infinitive.

The zero (or bare) infinitive is used after verbs of perception (see, feel, hear), many auxiliary verbs (may, should, must), the verbs make and let, and the expressions had better and would rather.

See also:

• Exercise in Identifying Infinitive Phrases
• Grammatical Zeros and Bare Relatives
• Passive Infinitive
• Ten Quick Questions and Answers About Verbs and Verbals
• Verbals
• What Is a "Split Infinitive" and What's Wrong With It?

Examples and Observations:

• Several witnesses saw the boy leave the sidewalk and run into the side of the bus.



• "I remember the first song I heard him sing: 'Mention Dirty to My Heart.'"
  (Alan Lomax speaking about Woody Guthrie)



• On Tuesday, the White House announced new steps to expand research into technology that would help capture and store carbon emitted by burning coal.



• The program has strengthened our economy and helped remedy past and present discrimination.



• "[I]t is sometimes possible to omit the infinitive marker to for the sake of a more harmonious-sounding construction. Grammarians call such infinitives without markers bare infinitives. The English language only allows us to omit the marker in infinitives placed after certain verbs in the active voice.
  
  "The following list of sentences illustrates a few of the verbs after which we may omit the infinitive marker. The verbs in italics are the verbs to note (they have been written again in parentheses in their present indicative forms at the ends of the sentences.) The words in bold are bare infinitives. The marker to is missing in each. Read every sentence twice, first without the marker and then with the marker restored. The bare versions are clearly preferable. . . .

  I felt her heart beat. (feel)
  
  We heard the birds whistle a merry tune. (hear). . .

  When these verbs are used in the passive voice, the marker to returns. . . .

  Her heart was felt to beat. (feel)
  
  The birds were heard to sing a merry tune. (hear) . . .

  (M. Strumpf and A. Douglas, The Grammar Bible. Owl Books, 2004)