Initialization Vector definition in Computer Security terms:
Definition(s): A binary vector used as the input to initialize the algorithm for the encryption of a plaintext block sequence to increase security by introducing additional cryptographic variance and to synchronize cryptographic equipment. The initialization vector need not be secret. Some of the Triple Data Encryption Algorithm Modes of Operation require 3 initialization vectors.
Source(s): NIST SP 800-20
A data block that some modes of operation require as an additional initial input.
Source(s): NIST SP 800-38A
A nonce that is associated with an invocation of authenticated encryption on a particular plaintext and AAD.
Source(s): NIST SP 800-38D
reference: CSRC Glossary