From WordNet (r) 2.0 (August 2003) [wn]:
extra
adj 1: further or added; "called for additional troops"; "need
extra help"; "an extra pair of shoes"; "I have no
other shoes"; "there are other possibilities" [syn:
{other(a)}, additional]
2: more than is needed, desired, or required; "trying to lose
excess weight"; "found some extra change lying on the
dresser"; "yet another book on heraldry might be thought
redundant"; "skills made redundant by technological
advance"; "sleeping in the spare room"; "supernumerary
ornamentation"; "it was supererogatory of her to gloat";
"delete superfluous (or unnecessary) words"; "extra ribs
as well as other supernumerary internal parts"; "surplus
cheese distributed to the needy" [syn: excess,
redundant, spare, supererogatory, superfluous,
supernumerary, surplus]
3: added to a regular schedule; "a special holiday flight";
"put on special buses for the big game" [syn: special]
n 1: a minor actor in crowd scenes [syn: supernumerary, {spear
carrier}]
2: an additional edition of a newspaper (usually to report a
crisis)
3: something additional of the same kind; "he always carried
extras in case of an emergency" [syn: duplicate]
adv : unusually or exceptionally; "an extra fast car"
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Extra- \Ex"tra-\ [L., fr. exter. See Exterior.]
A Latin preposition, denoting beyond, outside of; -- often
used in composition as a prefix signifying outside of,
beyond, besides, or in addition to what is denoted by the
word to which it is prefixed.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Extra \Ex"tra\, a.
Beyond what is due, usual, expected, or necessary;
additional; supernumerary; also, extraordinarily good;
superior; as, extra work; extra pay. "By working extra
hours." --H. Spencer.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Extra \Ex"tra\, n.; pl. Extras.
1. Something in addition to what is due, expected, or
customary; esp., an added charge or fee, or something for
which an additional charge is made; as, at some hotels air
conditioning is an extra.
[Webster 1913 Suppl.]
2. An edition of a newspaper issued at a time other than the
regular one.
[Webster 1913 Suppl.]
3. (Cricket) A run, as from a bye, credited to the general
score but not made from a hit.
[Webster 1913 Suppl.]
4. Something of an extra quality or grade.
[Webster 1913 Suppl.]
From The Free On-line Dictionary of Computing (19 Sep 2003) [foldoc]:
EXTRA
Object-oriented, Pascal style, handles sets. "A Data Model
and Query Language for EXODUS", M.J. Carey et al, SIGMOD 88
Conf Proc, pp.413- 423, ACM SIGMOD Record 17:3 (Sept 1988).