From The Collaborative International Dictionary of English v.0.48 [gcide]:
Confirmation \Con`fir*ma"tion\, n. [F. confirmation, L.
confirmatio.]
1. The act of confirming or strengthening; the act of
establishing, ratifying, or sanctioning; as, the
confirmation of an appointment.
[1913 Webster]
Their blood is shed
In confirmation of the noblest claim. --Cowper.
[1913 Webster]
2. That which confirms; that which gives new strength or
assurance; as to a statement or belief; additional
evidence; proof; convincing testimony.
[1913 Webster]
Trifles light as air
Are to the jealous confirmations strong
As proofs of holy writ. --Shak.
[1913 Webster]
3. (Eccl.) A rite supplemental to baptism, by which a person
is admitted, through the laying on of the hands of a
bishop, to the full privileges of the church, as in the
Roman Catholic, the Episcopal Church, etc.
[1913 Webster]
This ordinance is called confirmation, because they
who duly receive it are confirmed or strengthened
for the fulfillment of their Christian duties, by
the grace therein bestowed upon them. --Hook.
[1913 Webster]
4. (Law) A conveyance by which a voidable estate is made sure
and not voidable, or by which a particular estate is
increased; a contract, express or implied, by which a
person makes that firm and binding which was before
voidable.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
confirmation
n 1: additional proof that something that was believed (some
fact or hypothesis or theory) is correct; "fossils provided
further confirmation of the evolutionary theory" [syn:
confirmation, verification, check, substantiation]
2: information that confirms or verifies
3: making something valid by formally ratifying or confirming
it; "the ratification of the treaty"; "confirmation of the
appointment" [syn: ratification, confirmation]
4: a ceremony held in the synagogue (usually at Pentecost) to
admit as adult members of the Jewish community young men and
women who have successfully completed a course of study in
Judaism
5: a sacrament admitting a baptized person to full participation
in the church