From Tolkien Gateway

Ethuil is the Sindarin name for the season of spring; called Tuilë in Quenya. In the Reckoning of Rivendell it was the first season of the year, and corresponded more or less to the 54 days between 7 April and 30 May in the Shire Calendar.[1]


Calendar of Imladris
Meaning: 'First Day' 'Spring' 'Summer' 'Autumn' 'Middle Days' 'Fading' 'Winter' 'Stirring' 'Last Day'
Quenya: Yestarë Tuilë Lairë Yávië Enderi Quellë Hrívë Coirë Mettarë
Sindarin: Ethuil Laer Iavas Firith Rhîw Echuir