Becoming smaller, fewer, or less in amount, degree, or frequency over time; less and less.
From Latin 'decrescere' meaning 'to grow down or away,' from 'de-' (down, away) plus 'crescere' (to grow). The word mirrors 'increasingly' but with the opposite directional prefix, entering English in the 14th century through Old French.
While 'increasingly' is common in everyday speech, 'decreasingly' is surprisingly rare - we tend to say 'less and less' instead. This asymmetry might reflect human psychology: we notice growth more readily than decline, or perhaps we prefer the more concrete 'less' to the abstract concept of 'decreasing manner.'
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