Definitions

1. noun

a period of time in the past that was idyllically happy and peaceful

“She often reminisced about her halcyon days at summer camp.”

2. adjective

serenely happy and peaceful

“The halcyon atmosphere of the garden was a welcome escape from the city.”

3. noun

a type of bird, specifically a kingfisher, that is said to nest on the sea during the summer

“The halcyon is a bird known for its distinctive call.”