Forthy comes from Old English forþÄ« ('therefore, for that reason'), from for ('for') + þÄ« (instrumental case of þæt, 'that'). Morphologically, the form is compositional, with the named elements combining to produce the modern spelling and sense. In present use, it is used as a adverb and conjunction meaning "therefore; for that reason (archaic)", so the historical material remains connected with the current sense rather than standing as bare ancestry. The named historical forms include Old English forþÄ«, keeping the history tied to concrete forms rather than a loose resemblance. Its semantic neighborhood includes therefore, thus, hence, and wherefore, locating the modern specialization without adding a new origin story.