‘昆季’ is a classical, literary term meaning ‘brothers’, used especially in formal writing or respectful speech. The character 昆 (kūn) originally means ‘elder brother’ or ‘to be born together’, evoking kinship and shared origin; 季 (jì) traditionally denotes the youngest among siblings—literally ‘the last of the four seasons’, symbolizing the youngest child in a birth order. Together, 昆季 poetically encompasses brothers across the full spectrum of seniority, emphasizing familial harmony and seasonal metaphor rather than literal age sequence.

This term appears mainly in essays, epitaphs, letters, and ceremonial contexts—not in daily conversation. It carries warm respect and refined elegance, often paired with other classical terms like ‘昆仲’ (kūn zhòng, elder and middle brothers) or ‘伯仲叔季’ (bó zhòng shū jì, the four traditional birth-order titles). Learners should recognize it as a fixed, set phrase: it cannot be split, reordered, or modified with measure words or particles.