参考
さんこう · sankou · JLPT N3 · noun
mention
📖 参考 = compare (参) + think over (考): consult a source, then weigh it
参 means to join in or compare against; 考 means to think or examine, as in 考える (kangaeru). Checking something against a source and thinking it through is a reference. さんこう shares its こう with 思考 (shikou, thinking).
考 — old 老 (top) + 丂 phonetic
Originally written like 老 ('old'), 考 depicted an elderly person with long hair leaning on a cane, and the two characters were once interchangeable. Over time 考 specialized to mean 'deceased father' and later 'to examine, test, investigate,' with the bottom 丂 hinting at the sound.