WordNet (r) 3.0 (2006):

Theseus
    n 1: (Greek mythology) a hero and king of Athens who was noted
         for his many great deeds: killed Procrustes and the
         Minotaur and defeated the Amazons and united Attica

The Free On-line Dictionary of Computing (30 December 2018):

Theseus

    A language based on Euclid, never implemented.

   ["Theseus - A Programming Language for Relational Databases",
   J.E. Shopiro, ACM Trans Database Sys 4(4):493-517, Mar 1979].

   (1994-12-14)