have to

• hafta (informal, nonstandard)

• (UK) IPA^(key): /ˈhæv.tuː/ (careful)
• (General American) IPA^(key): /ˈhæf.tu/ (careful)

• Audio (US)

  (file)

• (UK, General American) IPA^(key): /ˈhæf.tə/ (relaxed pronunciation)

have to (third-person singular simple present has to, present participle having to, simple past and past participle had to)

1. Must; need to; urged to; to be required to. Indicates obligation.

   I just have to have that shirt;  you have to wear a seat belt

   I have to go to the bathroom.

   • 1897 December (indicated as 1898), Winston Churchill, chapter I, in The Celebrity: An Episode, New York, N.Y.: The Macmillan Company; London: Macmillan & Co., Ltd., →OCLC:

     I was about to say that I had known the Celebrity from the time he wore kilts. But I see I will have to amend that, because he was not a celebrity then, nor, indeed, did he achieve fame until some time after I left New York for the West.

   • 1951 September, “Notes and News: New Station for Glasgow Zoo”, in Railway Magazine, page 639:

     Before the new station could be built, a private overbridge had to be raised, and the railway regraded.

   • 2013 July-August, Henry Petroski, “Geothermal Energy”, in American Scientist, volume 101, number 4:

     Energy has seldom been found where we need it when we want it. Ancient nomads, wishing to ward off the evening chill and enjoy a meal around a campfire, had to collect wood and then spend time and effort coaxing the heat of friction out from between sticks to kindle a flame.

   • 2023 December 27, Stephen Roberts, “Bradshaw's Britain: the way to Weymouth”, in RAIL, number 999, page 55:

     The railway ran through the resort's narrow streets up to Weymouth Quay station, with thoughtlessly parked vehicles sometimes having to be bumped out of the way.

2. (with be) Must (logical conclusion).

   that has to be the postman;  it has to be an electrical fault

• have is always followed by an infinitive verb, unless the verb is assumed:

I don't want to go to school, but I have to.

("obligation"):

• have got to, got to, gotta
• must

("logical conclusion"):

• be bound to
• have got to, got to, gotta
• must

• Appendix:English modal verbs
• Appendix:English tag questions

• Collins English Dictionary
• “have to”, in Merriam-Webster Online Dictionary, Springfield, Mass.: Merriam-Webster, 1996–present.
• “have to”, in Dictionary.com Unabridged, Dictionary.com, LLC, 1995–present.