The Collaborative International Dictionary of English v.0.48:

Schema \Sche"ma\, n.; pl. Schemata, E. Schemas. [G. See
   Scheme.] (Kantian Philos.)
   An outline or image universally applicable to a general
   conception, under which it is likely to be presented to the
   mind; as, five dots in a line are a schema of the number
   five; a preceding and succeeding event are a schema of cause
   and effect.
   [1913 Webster]

WordNet (r) 3.0 (2006):

schema
    n 1: an internal representation of the world; an organization of
         concepts and actions that can be revised by new information
         about the world [syn: schema, scheme]
    2: a schematic or preliminary plan [syn: outline, schema,
       scheme]

The Free On-line Dictionary of Computing (19 January 2023):

schema

   1.  database schema.

   2.  axiom schema.

   3.  XML schema.