Present participle of guesstimate; the act of making rough estimates without precise information.
Regular present participle formation of 'guesstimate' using '-ing.' This verbal form functions as both a gerund (noun) and a progressive aspect marker.
The '-ing' form is remarkable because it's genuinely ambiguous in English—'guesstimating' can be a noun (the process), an adjective (a guesstimating approach), or part of a continuous verb—and context tells us which one, a feature that gives English tremendous flexibility.
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