sain (v.) Look up sain at Dictionary.com
"to cross oneself; to mark with the sign of the cross," Old English segnian, from Latin signare "to sign" (in Church Latin "to make the sign of the Cross"); see sign (n.). A common Germanic borrowing, cognate with Old Saxon segnon, Dutch zegenen, Old High German seganon, German segnen "to bless," Old Norse signa.