Synodic cycle
The time two planets take to go from one conjunction to the next.
Jupiter catches Saturn about every 20 years, Saturn catches Neptune about every 36, Uranus catches Pluto only every century or so.
When financial or mundane astrology talks about "cycles", this is usually what it means. Within one cycle the pair also forms a waxing square, an opposition and a waning square, much as the Moon goes from new to full and back.