Its pronunciation is T IY EH-R-iy- †. Thierry is used chiefly in the French language, and its origin is Old French and Gothic. Thierri (Old French) and Tierri (Old French) are old forms of Thierry. Thierry is a variant of the name Terry (English) in the French language.Thierry is also a variant of the name Theodoric (English) in the French language.Thierry has 14 variants. Variants include Theirry, Theory, Thery, Thierea, Thieree, Thierey, Thieri, Thierie, Thierrea, Thierree, Thierrey, Thierri, Thierrie, and Thiery. Thierry is unusual as a baby name for boys.hierry is also a variant of the name Theodoric (English) in the French language. Thierry has 14 variants. Variants include Theirry, Theory, Thery, Thierea, Thieree, Thierey, Thieri, Thierie, Thierrea, Thierree, Thierrey, Thierri, Thierrie, and Thiery.