In this Recommendation, a key-wrapping key is a symmetric key established through a key-agreement transaction and used with a key-wrapping algorithm to protect the keying material to be transported.
Source(s):
NIST SP 800-56A Rev. 2 [Superseded]

  A symmetric key-encrypting key that is used to provide both confidentiality and integrity protection. Also see Key-encrypting key.
Source(s):
NIST SP 800-57 Part 1 Rev. 4 [Superseded]

  A symmetric key used with a key-wrapping algorithm to protect keying material. In accordance with this Recommendation (SP 800-56B), a key-wrapping key can be established using a KAS1, KAS2 or KTS-OAEP scheme and then used with a key-wrapping algorithm to protect transported keying material. (See Section 9.3.)
Source(s):
NIST SP 800-56B Rev. 2

  A symmetric key that is used with a key-wrapping algorithm to protect the confidentiality and integrity of keys.
Source(s):
NIST SP 800-57 Part 2 Rev.1 under Key wrapping key

  A symmetric key used to provide confidentiality and integrity protection for other keys.
Source(s):
NIST SP 800-175B Rev. 1

  A symmetric key that is used to provide both confidentiality and integrity protection for other keys. Also see Key-encrypting key.
Source(s):
NIST SP 800-57 Part 1 Rev. 5

  A key used as an input to a key-wrapping method; see SP 800-38F.
Source(s):
NIST SP 800-133 Rev. 2

  In this Recommendation, a key-wrapping key is a symmetric key established during a key-transport transaction and used with a key- wrapping algorithm to protect the keying material to be transported.
Source(s):
NIST SP 800-56B Rev. 1 [Superseded]

  A symmetric key-encrypting key.
Source(s):
NIST SP 800-57 Part 1 Rev. 3 [Superseded]