The period during which someone or something exists.

• term
• span
• lifetime
• life
• existence
• Often used in plural: duration

A particular time notable for its distinctive characteristics

• time
• period
• era
• epoch
• age

The period of the earth's revolution

• date
• diurnal course
• astronomical day
• civil day
• natural day
• nautical day
• solar-day
• period from dawn to dark
• time between sunrise and sunset
• sidereal day
• mean-solar-day
• twenty-four hours

The time of light or work

• good day for the races
• scorcher
• day; sizzler
• /etc
• damp
• cold
• hot
• bad
• union day; good
• eight-hour day
• broadcast day
• daylight hours
• working-day
• workday
• full-day
• broad-daylight
• daytime
• daylight

A special day

• festival
• celebration
• holiday

A period of time

• prime
• heyday
• time
• era