Halcyon and Low-key

Halcyon adjective - Free from storms or physical disturbance.

Low-key and halcyon are semantically related. In some cases you can use "Low-key" instead an adjective "Halcyon".

Low-key adjective - Not excessively showy.

Halcyon and low-key are semantically related. Sometimes you can use "Halcyon" instead an adjective phrase "Low-key".