In a friendly manner; with regard to friendship (archaic or dialectal form).
From 'friendly' plus the suffix '-wise' (Old English 'wisan', meaning way or manner, also meaning to turn). The '-wise' suffix was productive in Middle English but is now rare.
The '-wise' suffix created tons of adverbs in Middle English (likewise, otherwise, clockwise), but friendliwise never caught on—showing that not all grammatical possibilities become actual words.
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