ADVERB (2)

1. in theory; according to the assumed facts;
- Example: "on paper the candidate seems promising"

2. in a theoretical manner;
- Example: "he worked the problem out theoretically"

The Collaborative International Dictionary of English v.0.48:

Theoretic \The`o*ret"ic\, Theoretical \The`o*ret"ic*al\, a. [Gr.
   ?: cf. L. theoreticus, F. th['e]or['e]tique.]
   Pertaining to theory; depending on, or confined to, theory or
   speculation; speculative; terminating in theory or
   speculation: not practical; as, theoretical learning;
   theoretic sciences. -- The`o*ret"ic*al*ly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

theoretically
    adv 1: in theory; according to the assumed facts; "on paper the
           candidate seems promising"
    2: in a theoretical manner; "he worked the problem out
       theoretically" [ant: by trial and error, empirically,
       through empirical observation]