对照 (duìzhào) literally combines 对 (duì, 'face-to-face' or 'opposite') and 照 (zhào, 'to shine' or 'to reflect'), evoking the image of two things placed side by side so they can be seen clearly together — like light illuminating both for direct comparison. As a verb, it means 'to compare (two things systematically)' or 'to check against a standard or reference.' It implies careful, often analytical, side-by-side examination — not casual observation.

This word is frequently used in academic, technical, medical, or administrative contexts: comparing data sets, verifying documents against originals, matching symptoms to diagnostic criteria, or aligning translations with source texts. It can also function as a noun meaning 'a comparative reference' (e.g., a对照 table), but its primary and most common use is verbal. Unlike the more general 比较 (bǐjiào), 对照 stresses precision, alignment, and verification against an authoritative model or baseline.