'pithily' originates from English, specifically the adjective 'pithy', where the root 'pith' meant 'essential part, core' (from Old English 'piþa').

'pithily' changed from the Early Modern English adjective 'pithy' (mid-17th century), which itself was formed from Old English 'piþa' meaning 'pith, core'; the adverb 'pithily' was created by adding the suffix '-ly' to 'pithy'.

Initially, related to the literal 'pith' (the central or essential part) and thus implied substance or substance-bearing quality; over time it evolved to mean 'expressing much in few words'—concise and forceful expression.