upstart

Short definition from Wiktionary

Noun

1. 1
   One who has suddenly gained wealth, power, or other prominence, but either has not received social acceptance or has become arrogant or presumptuous.
2. 2
   The meadow saffron.

Adjective

1. 1
   Acting like a parvenu.
2. 2
   Self-important and presumptuous.

Verb

1. 1
   To rise suddenly, to spring