1. a symbol that establishes the identity of the one bearing it;
WordNet (r) 3.0 (2006):
n 1: a symbol that establishes the identity of the one bearing
The Free On-line Dictionary of Computing (18 March 2015):
1. A formal name used in
source code to refer to a variable, function,
procedure, package, etc. or in an operating system to
refer to a process, user, group, etc.
Each different type of entity may have a different range of
valid identifiers or "name space". For example, an identifier
in C is a series of one or more letters, digits and
underscores that does not begin with a digit. An identifier
has a type, e.g. integer variable, hash, variant and a
scope, e.g. block, global.
2. (id) A primary key. The column containing a
table's primary key is frequently named after the table with
"_id" appended, e.g. "customer_id".