A handclasp used to signify a pledge, such as a contract or marriage.
A firm hold, as with the hands.
A contract, esp. of marriage or betrothal, confirmed by a handclasp.
Betrothed or married.
To betroth or marry by joining hands.
Origin of handfast
From Middle English hondfast past participle of hondfesten to betroth from Old Norse handfesta to strike a bargain, pledge hönd hand festa to fasten, fix, affirm past- in Indo-European roots