  The use of the symbol $\lor$ for disjunction in formal logic is ubiquitous.
Where did it come from? Some sources say it was introduced by Peano; others
suggest it that it originates as an abbreviation of the Latin word for "or",
vel. The origin of the symbol can be traced to Russell's first investigations
into formal logic. Because of Principia, Russell's notation was influential in
mathematical logic (through the work of the Hilbert school) as well as
philosophy (the logical empiricists in the 1920s and 1930s, especially Carnap
and early Quine).
