Wordnet 3.0
NOUN (1)
1. 
 the liturgical language of the Coptic Church used in Egypt and Ethiopia; 
 written in the Greek alphabet; 
ADJECTIVE (1)
1. 
 of or relating to the Copts or their church or language or art; 
- Example: "the distinctive Coptic art of 6th-century Christian Egypt"
The Collaborative International Dictionary of English v.0.48:
Coptic \Cop"tic\ (k[o^]p"t[i^]k), a. [Abbrev. from L. Aegyptius
   an Egyptian, Gr. ?, Ar. kibt[imac], pl. kibt.]
   Of or pertaining to the Copts. -- n. The language of the
   Copts.
   [1913 Webster]
WordNet (r) 3.0 (2006):
Coptic
    adj 1: of or relating to the Copts or their church or language
           or art; "the distinctive Coptic art of 6th-century
           Christian Egypt"
    n 1: the liturgical language of the Coptic Church used in Egypt
         and Ethiopia; written in the Greek alphabet