Constant is an IMGT keyword which may refer to:
- a gene: C-GENE
- an exon: C exons have specific names depending from the IG or TR chains
- a region: C-REGION
- a domain: C-DOMAIN of the immunoglobulin (IG) and T cell receptor (TR) chains
(encoded by the C-REGION, most to the C-REGION or part of the C-REGION, depending on the IG or TR chains).
Note that "C-LIKE-DOMAIN" refers to the C-like domain of IgSF proteins other than IG or TR.