Concordance can mean:

• Concordance (publishing) — a list of words used in a body of work, with their immediate contexts.
• Concordance (genetics) — the presence of the same trait in both members of a pair of twins (or set of individuals).
• Concordance (medicine) — involvement of the patient in decision making to improve treatment Compliance (medicine)
• Grammatical agreement — in linguistics, a form of cross-reference between related words.
• Inter-rater reliability — in statistics, the degree to which multiple measurements of the same thing are similar. Or more specifically: