Describes a surface that is even and flat, or a state of mind or atmosphere that is calm and untroubled. Often used in literary or slightly formal contexts.
This land is level and suitable for building a house.
His mind is always calm.
Irregular okurigana usage; less common than 平らか.
Derived from the adjective stem 平ら (たいら, 'flat') + suffix か, forming a classical adjectival noun. The exact historical development is uncertain.