(adj): vs. fat), lean -- (lacking excess flesh
(adj): more than is needed, desired, or required
(adj): vs. necessary), unneeded -- (not necessary
(adj): not taken up by scheduled activities
(adj): vs. occupied) -- (not held or filled or in use
(adj): kept in reserve especially for emergency use
(adj): vs. necessary), unneeded -- (not necessary
(adj): prenominal), scanty, spare -- (lacking in amplitude or quantity
(adj): vs. ample), meagre, meagerly, stingy, scrimpy -- (deficient in amount or quality or extent
(adj): lacking embellishment or ornamentation
(adj): vs. adorned), undecorated -- (not decorated with something to increase its beauty or distinction
(v): refrain from harming
(v): resist doing something
(v): save or relieve from an experience or action
(v): grant relief or an exemption from a rule or requirement to
(v): give up what is not strictly needed
(v): transfer possession of something concrete or abstract to somebody
(v): use frugally or carefully
(v): use up, consume fully
(n): an extra component of a machine or other apparatus
(n): an artifact that is one of the individual parts of which a composite entity is made up; especially a part that can be separated from or attached to a system
(n): an extra car wheel and tire for a four-wheel vehicle
(n): a wheel that has a tire and rim and hubcap; used to propel the car
(n): a score in tenpins; knocking down all ten after rolling two balls
(n): the act of scoring in a game or sport
Contronymic in the sense: lean vs. excess (to spare).