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.

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Definitions of friendly from WordNet
friendly (adj.)
characteristic of or befitting a friend;
a friendly neighborhood
a friendly host and hostess
friendly advice
the only friendly person here
friendly (adj.)
inclined to help or support; not antagonistic or hostile;
a government friendly to our interests
Synonyms: well-disposed / well disposed
friendly (adj.)
easy to understand or use;
user-friendly computers
a consumer-friendly policy
a reader-friendly novel
friendly (adj.)
of or belonging to your own country's forces or those of an ally;
in friendly territory
he was accidentally killed by friendly fire
friendly (n.)
troops belonging to or allied with your own military forces;