Friendly

wiktionary

ref

From Middle English frendly, freendly, frendely, frendlich, from Old English frēondlīċ, from Proto-Germanic *frijōndlīkaz, equivalent to friend +‎ -ly. Cognate with Saterland Frisian früntelk, fjuntelk(“friendly”), West Frisian freonlik(“friendly”), Dutch vriendelijk(“friendly”), German Low German fründelk, frünnelk(“friendly”), German freundlich(“friendly”).

From Middle English frendly, frendliche, from Old English frēondlīċe(“in a friendly manner”), equivalent to friend +‎ -ly.

etymonline

ref

friendly (adj.)

Old English freondlic "well-disposed, kindly;" see friend (n.) + -ly (1). Related: Friendlily; friendliness. As an adverb Old English had freondliche, but by 14c. as the inflections wore off in English it had become indistinguishable from the adjective. Probably owing to that it is rare in modern use; friendfully (mid-15c.) and the correct but ungainly friendlily (1670s) never caught on.