spare

from The American Heritage® Dictionary of the English Language, 5th Edition.

• transitive verb To refrain from harming, injuring, destroying, or killing.
• transitive verb To leave undamaged or unharmed.
• transitive verb To refrain from denouncing or distressing; treat leniently or with consideration.
• transitive verb To allow (someone) to avoid experiencing or doing (something).
• transitive verb To hold back from; withhold or avoid.
• transitive verb To use or supply with restraint.
• transitive verb To give or grant out of one's resources; afford.
• adjective Kept in reserve.
• adjective Being in excess of what is needed; extra.
• adjective Free for other use; unoccupied.
• adjective Not lavish, abundant, or excessive; meager.
• adjective Lean and trim.
• adjective Not elaborate or ornate; simple.
• noun A replacement, especially a tire, reserved for future need.
• noun The act of knocking down all ten pins with two successive rolls of a bowling ball.
• noun The score so made.
• idiom (to spare) In addition to what is needed.

from The Century Dictionary.

• To be frugal, saving, or chary of; refrain from employing freely; use or dispense with moderation.
• To dispense with; give or yield up; part with the use, possession, or presence of; do without, as for a motive or because of superfluity.
• To withhold the use or doing of; refrain from; omit; forbear; forego: often with a second (indirect) object.
• To refrain from injury to; leave unhurt or undisturbed; forbear from harming or destroying; treat with moderation or consideration; withhold severity or exaction from; refrain from unkindness to; specifically, to allow to live.
• Used reflexively, to be sparing of one's self; be chary or diffident; act with reserve.
• To be frugal or saving; economize: act parsimoniously or stingily.
• To withhold action of any kind; refrain from the doing of something, especially something harmful or harsh; hold one's hand; keep quiet; hold off.
• Scanty; meager; frugal; not plentiful or abundant: as, a spare diet.
• Lacking in substance; lean; gaunt; poor; thin; flimsy.
• Reserved; chary; cautious.
• That may be spared, dispensed with, or applied to a different purpose; not needed for regular or appointed uses; superabundant: as, spare time for recreation; spare cash.
• Reserved front common use; provided or held for extra need; not regularly required: as, a spare anchor; a spare umbrella.
• In zoology, sparingly distributed; remote from one another; few in number; sparse: as, spare hairs, spots, or punctures.
• noun Frugal use: saving economy; moderation; restraint.
• noun In American holding, an advantage gained by the knocking down of all the pins by rolling two balls: as, to make a spare.
• noun An opening in a gown or petticoat; a placket.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb To use frugally or stintingly, as that which is scarce or valuable; to retain or keep unused; to save.
• transitive verb To keep to one's self; to forbear to impart or give.
• transitive verb To preserve from danger or punishment; to forbear to punish, injure, or harm; to show mercy to.
• transitive verb To save or gain, as by frugality; to reserve, as from some occupation, use, or duty.
• transitive verb To deprive one's self of, as by being frugal; to do without; to dispense with; to give up; to part with.
• transitive verb [Obs.] To save one's self labor, punishment, or blame.
• intransitive verb To be frugal; not to be profuse; to live frugally; to be parsimonious.
• intransitive verb To refrain from inflicting harm; to use mercy or forbearance.
• intransitive verb obsolete To desist; to stop; to refrain.
• noun obsolete The act of sparing; moderation; restraint.
• noun obsolete Parsimony; frugal use.
• noun obsolete An opening in a petticoat or gown; a placket.