Mid 18th century; earliest use found in William Robertson (1721–1793), historian and Church of Scotland minister. From post-classical Latin praetaxation-, praetaxatio prior evaluation, previous agreement from praetaxat-, past participial stem of praetaxare to count, reckon, or estimate beforehand, to determine, to mention previously + classical Latin -iō; compare taxation. The intermediate sense was apparently that of giving a preliminary opinion.