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[ noun ]
the sterilization of an animal
<noun.act>
they took him to the vet for neutering

Alter \Al"ter\, v. t. [imp. & p. p. {Altered}; p. pr. & vb. n.
{Altering}.] [F. alt['e]rer, LL. alterare, fr. L. alter
other, alius other. Cf. {Else}, {Other}.]
1. To make otherwise; to change in some respect, either
partially or wholly; to vary; to modify. ``To alter the
king's course.'' ``To alter the condition of a man.'' ``No
power in Venice can alter a decree.'' --Shak.

It gilds all objects, but it alters none. --Pope.

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.] --Milton.

3. To geld. [Colloq.]

Syn: {Change}, {Alter}.

Usage: 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.