Webster's Revised Unabridged Dictionary · 1913

Seasonal

Seasonal , adjective

1.
Of or pertaining to the seasons.
2.
Occurring or being used in a specific season; as, seasonal items for sale.
Collocations (1)
Seasonal dimorphism (Zoology) , the condition of having two distinct varieties which appear at different seasons, as certain species of butterflies in which the spring brood differs from the summer or autumnal brood.