propellerhead

/P R AH0 P EH1 L ER0 HH EH0 D/
noun
  1. 1

    The hub of a propeller

  2. 2

    The central part of a propeller, into which the blades fit

  3. 3

    A person deeply absorbed in an academic field or technical interest, especially to the exclusion of social activities.

Source: https://en.wiktionary.org/wiki/propeller%20head, https://en.wiktionary.org/wiki/propellerhead