Definition 1: Quarrelsome, argumentative for no reason; given to opposing whatever is said or done.

Usage 1: The verb is "contend" (to compete for control, to challenge, to strive in opposition to). The noun "contention" is derived from the verb and "contentious" is derived from the noun. Do not confuse this word with "conscientious" (following the dictates of one's conscience, assiduous). Working conscientiously is a good thing; working contentiously is counterproductive.

Suggested usage: Hopefully, you will have no use for this word except metaphorical use. "I have a contentious door that will only open half way" suggests the door resists attempts to open it. "My car can be contentious on cold, winter mornings," means it often opposes being started. Contentious friends and co-workers no one needs.

Etymology: Latin con- "with" + tendere "to stretch, extend." Akin to tenuis "thin" via the PIE root *ten- which also underlies English "thin," and Greek tenon "tendon," ton-e "stretching a note at the same pitch," and ton-os "a cord, band" (that which may be stretched). (See "How is a Hippopotamus like a Feather?" in yourDictionary.com's library for more on PIE.)