A person who relies on guesswork rather than systematic knowledge or precise methods in their work.
From 'guesswork' (the practice of guessing) plus '-er' (agent suffix). 'Guesswork' itself combines 'guess' with 'work,' a compound that emerged in the 16th century.
The term 'guessworker' is quite rare, which is interesting linguistically—compound agents like 'guessworker' are logically possible but communities of speakers often develop other words to fill the slot (like 'charlatan' or 'bungler'), showing that logical formation isn't the only factor in vocabulary selection.
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