See also the related category basque.
Seyn is not widely used as a baby name for boys. It is not in the top 1000 names.
Baby names that sound like Seyn include Seain, Seaine, Sahn (Vietnamese), Sam (English), Samín, Samm, San, Scan, Schamane, Schaun, Sean (English and Irish), Seane, Seán (English, Gaelic, and Irish), Seghyn, Sein, Sem (English, Dutch, and German), Sen, Senán (Irish), Séan, and Shaan (Hebrew).
† approx English pronunciation for Seyn: S as in "see (S.IY)" ; EY as in "ate (EY.T)" ; N as in "knee (N.IY)"