upstart (n.)

1550s, "one newly risen from a humble position to one of power, importance, or rank, a parvenu," also start-up, from up (adv.) + start (v.) in the sense of "jump, spring, rise." As an adjective from 1560s. Compare the archaic verb upstart "to spring to one's feet," attested from c. 1300.

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Definitions of upstart from WordNet
upstart (n.)
an arrogant or presumptuous person;
upstart (n.)
a person who has suddenly risen to a higher economic status but has not gained social acceptance of others in that class;
Synonyms: parvenu / nouveau-riche / arriviste
upstart (n.)
a gymnastic exercise performed starting from a position with the legs over the upper body and moving to an erect position by arching the back and swinging the legs out and down while forcing the chest upright;
Synonyms: kip
upstart (adj.)
characteristic of someone who has risen economically or socially but lacks the social skills appropriate for this new position;
Synonyms: nouveau-riche / parvenu / parvenue