epochal (adj.)

• alternate
• circling
• consequential
• cyclic
• even
• important
• intermittent
• isochronal
• measured
• momentous
• oscillatory
• periodical
• reciprocal
• recurrent
• recurring
• rhythmic
• rotary
• seasonal
• serial
• steady
• undulant
• undulatory
• unmatched
• unparalleled
• wavelike
• wheeling