In a manner that is prone to breaking; in a way that demonstrates fragility or ease of breaking.
From 'breakable' plus '-ly' (Old English '-lice'), the standard adverb-forming suffix. Rare in actual usage but grammatically regular.
This adverb is almost never used because we don't normally describe actions as happening 'breakably'—it shows the limits of how far English word-building rules can actually stretch.
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