Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Scrabble
  • Spanish Central
  • Learner's Dictionary


transitive verb sub·tend \səb-ˈtend\

Definition of subtend

  1. 1a :  to be opposite to and extend from one side to the other of <a hypotenuse subtends a right angle>b :  to fix the angular extent of with respect to a fixed point or object taken as the vertex <a central angle subtended by an arc> <the angle subtended at the eye by an object of given width and a fixed distance away>c :  to determine the measure of by marking off the endpoints of <a chord subtends an arc>

  2. 2a :  to underlie so as to includeb :  to occupy an adjacent and usually lower position to and often so as to embrace or enclose <a bract that subtends a flower>

Origin and Etymology of subtend

Latin subtendere to stretch beneath, from sub- + tendere to stretch — more at thin

First Known Use: 1570

Seen and Heard

What made you want to look up subtend? Please tell us where you read or heard it (including the quote, if possible).


a great number

Get Word of the Day daily email!