last spring; the spring of last year
A straightforward temporal noun/adverb meaning the spring of the previous year. Used in both formal and everyday contexts.
He graduated from university last spring.
Last spring, we planted cherry trees in this park.
The event last spring was a great success.
I started a new job since last spring.
今春 refers to this spring, whereas 昨春 refers to last spring, the previous year's spring.
Compound of 昨 (saku, 'last, previous') and 春 (shun, 'spring'). The reading is the on'yomi of both characters.