The description of the word you requested from the astronomical dictionary is given below.
peri- = [Greek] around; hapsis = [Greek] connection
The perifocus is the point in an orbit around a celestial body that is closest to the celestial body. The opposite point is the apofocus. For some celestial bodies more specific names are available that refer to just those bodies, for example perihelion for the Sun, perigee for the Earth, periselene for the Moon, perijove for Jupiter, or periastron for stars.