癸 is the LAST of the ten 天干 (Heavenly Stems): 甲乙丙丁戊己庚辛壬癸. Paired with the twelve 地支 (Earthly Branches) it builds the sixty-year sexagenary cycle that times traditional Chinese calendars, divination, and Chinese-zodiac years.
usage
Modern uses: dating historical events (癸丑, 癸卯, 癸酉 — each occurs every 60 years), Chinese-medicine and 易经 writing, and as a list-marker (Chinese equivalent of 'J' or item 10). In ordinary modern speech it's almost never used solo.
Components
pictograph
癸guǐ
tenth Heavenly Stem
Single self-component — the oracle-bone form drew four cross-pointed blades meeting at a center, possibly an 戣 (an ancient cross-bladed halberd) — by extension the tenth and final Heavenly Stem. Indexed under Kangxi #105 癶 (the two outward-pointing feet at the top); the radical isn't transparently meaningful in the modern shape, only a graphic match.
Filed under radical 癶 (bō, #105) by convention. 癶 is not a separate component in 癸, so no strokes are highlighted.
