Meaning of open sentence

o'pen sen'tence

Pronunciation: [key]
  1. an equation or inequality containing one or more variables in which its truth or falsehood depends upon the values assumed by the variables in a particular instance, as the equation x + 3 = 8.
  2. a propositional function that contains a free variable, as “x is a man.”
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.