friendly has 2 distinct synonyms spread across 1 of its 5 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its 2 recorded opposites are unfriendly, hostile.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
characteristic of or befitting a friend
“friendly advice”
inclined to help or support; not antagonistic or hostile
“a government friendly to our interests”
easy to understand or use
“user-friendly computers”
Synonyms, antonyms and the broader and narrower relations for friendly come from Princeton University’s WordNet. Full sources and licences.
of or belonging to your own country's forces or those of an ally
“in friendly territory”
troops belonging to or allied with your own military forces
“friendlies came to their rescue”