The descending wedge symbol ∨ may represent:
Logical disjunction in propositional logic
Join in lattice theory
The wedge sum in topology
The V sign, a symbol representing peace among other things
The vertically reflected symbol, ∧, is a wedge, and often denotes related or dual operators.
The ∨ symbol was introduced by Russell and Whitehead in Principia Mathematica, where they called it the Logical Sum or Disjunctive Function.
In Unicode the symbol is encoded . In TeX, it is \vee or \lor.
One motivation and the most probable explanation for the choice of the symbol ∨ is the latin word "vel" meaning "or" in the inclusive sense. Several authors use "vel" as name of the "or" function.