What is a supermoon?

Jean Meeus, Astronomical Algorithms book (Chapter 48, Perigee and Apogee of the Moon) calculated the lunar perigee and apogee for the period 1500 AD through 2500 AD. Closest approach to Earth using their centers is on 01-January-2257 at 356371 km. Farthest is on 07-January-2266 at 406720 km. The angular size difference is 4.151 arcminute. Max is 33.53 arcminute, min 29.379 arcminute. Lunar perigee this month is 07-April-2020 at 1800 UT, distance 356907 km, angular size 33.48 arcminute. April issue of Sky & Telescope magazine, page 42.

Early today I viewed Mars, Saturn, and Jupiter with my telescope, 0515-0600 EDT, lovely views before clouds started moving in. The waxing gibbous Moon very low in west, setting about 0611 EDT. That moon looked huge (ginormous) to my unaided eyes, perhaps a close super duper-moon :)