WordNet sense 1 (concerned with theory and data rather than practice; opposed to applied):

pure

WordNet sense 2 (hypothetical or theoretical and not expected to produce an immediate or practical result):

academic

WordNet sense 3 (dealing with a subject in the abstract without practical purpose or intention):

abstract, abstract

WordNet sense 4 (highly abstract and overly theoretical):

metaphysical

WordNet sense 5 (not based on fact or investigation):

notional, speculative

WordNet sense 6 (concerned primarily with theories or hypotheses rather than practical considerations):

theoretic