1. <programming> (or "monadic") A description of a
function or operator which takes one argument, e.g. the
unary minus operator which negates its argument. The term is
part of the same sequence as nullary and binary.
2. <data, humour> Base one. A number base with only one
digit, namely zero, and which can therefore only be used to
express the number zero. Attempting to add one to zero
results in an infinite sequence of carries. Numbers in unary
notation can be represented particularly efficiently however
since each digit requires no storage.
