the fading of spring; spring's departure
Poetic noun referring to the end of spring, often with a sense of transience and gentle melancholy. Common in classical poetry and literary contexts.
行く春を惜しむ歌が多く詠まれた。
Many poems were composed lamenting the passing of spring.
Looking up at the sky of the departing spring, I felt a little lonely.
Compound of 行く (iku/yuku, 'to go') and 春 (haru, 'spring'), literally 'departing spring'. The reading ゆく is a slightly older or more literary variant of いく.