1) Above all 2) At first 3) Chiefly 4) Chiefly, for the most part 5) Essentially 6) First and foremost 7) For the most part 8) In chief 9) In the first instance 10) In the main 11) Largely 12) Mainly 13) Mostly 14) Of primary import 15) Predominantly 16) Principally Found on https://www.crosswordclues.com/clue/primarily
Pri'ma·ri·ly adverb In a primary manner; in the first place; in the first place; in the first intention; originally. Found on http://www.encyclo.co.uk/webster/P/161
essentially; mostly; chiefly; principally: They live primarily from farming. · in the first instance; at first; originally: Primarily a doctor, he later became a lawyer. Found on https://www.infoplease.com/dictionary/primarily