Numbers 10:10
Also in the day of your gladness, and in your solemn days, and in the beginnings of your months, you shall blow with the trumpets over your burnt offerings, and over the sacrifices of your peace offerings; that they may be to you for a memorial before your God: I am the LORD your God.
Torrey's Topical Textbook—AKJV

Hosea 9:5
What will you do in the solemn day, and in the day of the feast of the LORD?
Torrey's Topical Textbook—AKJV