Alter

Al·ter

Alter

v. t.

imp. & p. p. Altered; p. pr. & vb. n. Altering

  1. To make otherwise; to change in some respect, either partially or wholly; to vary; to modify.
    It gilds all objects, but it alters none.
    My covenant will I not break, nor alter the thing that is gone out of my lips.
    — Ps. lxxxix. 34.
  2. To agitate; to affect mentally. [Obs.]
  3. To geld. [Colloq.]
Syn. -- Change, Alter.

Change is generic and the stronger term. It may express a loss of identity, or the substitution of one thing in place of another; alter commonly expresses a partial change, or a change in form or details without destroying identity.

Alter

v. i.
  1. To become, in some respects, different; to vary; to change; as, the weather alters almost daily; rocks or minerals alter by exposure.