spare

nouns

an extra component of a machine or other apparatus
an extra car wheel and tire for a four-wheel vehicle
a score in tenpins; knocking down all ten after rolling two balls
is a type of (narrower)
the act of scoring in a game or sport
"the winning score came with less than a minute left to play"

verbs

refrain from harming
is derived from
save or relieve from an experience or action
"I'll spare you from having to apologize formally"
is a type of (narrower)
grant relief or an exemption from a rule or requirement to
"She exempted me from the exam"
give up what is not strictly needed
"he asked if they could spare one of their horses to speed his journey"
use frugally or carefully
is a type of (narrower)
use up, consume fully
"The legislature expended its time on school questions"

adjectives

thin and fit
"the spare figure of a marathon runner"; "a body kept trim by exercise"
is derived from
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"
not taken up by scheduled activities
"a free hour between classes"; "spare time on my hands"
kept in reserve especially for emergency use
"a reserve supply of food"; "a spare tire"; "spare parts"
is similar to
not necessary
lacking in amplitude or quantity
"a bare livelihood"; "a scanty harvest"; "a spare diet"
is derived from
lacking embellishment or ornamentation
"a plain hair style"; "unembellished white walls"; "functional architecture featuring stark unornamented concrete"