self-important

From self- +‎ important.

self-important (comparative more self-important, superlative most self-important)

1. Having, or behaving as if having, too high of an opinion of one's own importance.

   Synonyms: conceited, haughty, pompous

   The assistant manager was a self-important fellow who strutted about the office barking instructions.

   • 1951 October, R. S. McNaught, “Lines of Approach”, in Railway Magazine, page 704:

     But despite its plague of tunnels, the run-in on this route is of unusual interest to the locomotive enthusiast: besides the hordes of self-important saddle-tanks shunting in the extensive yards, there was at one time the chance of seeing those slender little North London engines, with their large outside cylinders and no visible storage place for coal, and also an occasional South Eastern locomotive sporting a lot of polished brass.

• self-importantly