The Collaborative International Dictionary of English v.0.48:

Adhere \Ad*here"\, v. i. [imp. & p. p. Adhered; p. pr. & vb.
   n. Adhering.] [L. adhaerere, adhaesum; ad + haerere to
   stick: cf. F. adh['e]rer. See Aghast.]
   1. To stick fast or cleave, as a glutinous substance does; to
      become joined or united; as, wax to the finger; the lungs
      sometimes adhere to the pleura.
      [1913 Webster]

   2. To hold, be attached, or devoted; to remain fixed, either
      by personal union or conformity of faith, principle, or
      opinion; as, men adhere to a party, a cause, a leader, a
      church.
      [1913 Webster]

   3. To be consistent or coherent; to be in accordance; to
      agree. "Nor time nor place did then adhere." "Every thing
      adheres together." --Shak.
      [1913 Webster]

   Syn: To attach; stick; cleave; cling; hold
        [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

ADHERING. Cleaving to, or joining; as, adhering to the enemies of the United
States.
     2. The constitution of the United States, art. 3, s 3, defines treason
against the United States, to consist only in levying war against them or in
adhering to their enemies, giving them aid and comfort.
     3. The fact that a citizen is cruising in an enemy's ship, with a
design to capture or destroy American ships, would be an adhering to the
enemies of the United States. 4 State Tr. 328 ; Salk. 634; 2 Gilb. Ev. by
Lofft, 798.
     4. If war be actually levied, that is, a body of men be actually
assembled for the purpose of effecting by force a treasonable enterprise,
all those who perform any part, however minute, or however remote from the
scene of action, and who are leagued in the general conspiracy are to be
considered as traitors. 4 Cranch. 126.