'blotchily' originates from English, specifically formed from the adjective 'blotchy' plus the adverbial suffix '-ly'.

'blotchy' developed from the noun 'blotch' (Middle English 'blotche'/'blotch'), which itself is related to 'blot' (an old word for a stain or blot); the adverb 'blotchily' is a later formation adding '-ly' to the adjective.

Initially related to the noun 'blotch' meaning 'a stain or patch,' the sense evolved into describing things 'marked with irregular spots'; 'blotchily' now means 'in an irregularly spotted or patchy manner.'