forthy
Forthy (adv) means used to say this is the reason for something; therefore.
Etymology
This word comes from Middle English forthy, from Old English forþȳ, for þȳ þe, forþon (“because, since”), from for + þȳ, þon (“by that, therefore”), the instrumental case of þæt (“that”). It is related to Yola farthoo (“why”) and Old Norse fyrir því (at) (Danish and Norwegian fordi (“because”), Swedish för att). See also for, the, that.