Source : Webster's Revised Unabridged Dictionary (1913)

Adjunct \Ad"junct`\, a. [L. adjunctus, p. p. of adjungere. See
   {Adjoin}.]
   Conjoined; attending; consequent.

         Though that my death were adjunct to my act. --Shak.

   {Adjunct notes} (Mus.), short notes between those essential
      to the harmony; auxiliary notes; passing notes.

Adjunct \Ad"junct`\, n.
   1. Something joined or added to another thing, but not
      essentially a part of it.

            Learning is but an adjunct to our self. --Shak.

   2. A person joined to another in some duty or service; a
      colleague; an associate. --Wotton.

   3. (Gram.) A word or words added to quality or amplify the
      force of other words; as, the History of the American
      Revolution, where the words in italics are the adjunct or
      adjuncts of ``History.''

   4. (Metaph.) A quality or property of the body or the mind,
      whether natural or acquired; as, color, in the body,
      judgment in the mind.

   5. (Mus.) A key or scale closely related to another as
      principal; a relative or attendant key. [R.] See
      {Attendant keys}, under {Attendant}, a.

Source : WordNet®

adjunct
     adj 1: relating to something that is added but is not essential;
            "an ancillary pump"; "an adjuvant discipline to forms
            of mysticism"; "The mind and emotions are auxilliary
            to each other" [syn: {accessory}, {ancillary}, {adjuvant},
             {appurtenant}, {auxiliary}, {subsidiary}]
     2: of or relating to a person who is subordinate to another
        [syn: {assistant}]

adjunct
     n 1: something added to another thing but not an essential part
          of it
     2: a person who is an assistant or subordinate to another
     3: a construction that is part of a sentence but not essential
        to its meaning and can be omitted without making the
        sentence ungrammatical