午睡 is read as ごすい (gosui) and means nap.
ごすい
gosui
ごほう
noon gun
じゅくすい
deep sleep
いっすい
wink of sleep
ごご
afternoon
ごぜん
morning
うま
fifth month of the lunar calendar
ごぜんちゅう
in the morning
ごぜんさま
coming home after midnight
ごごれいじ
noon
ごぜんれいじ
midnight
ごごいち
first thing in the afternoon
ごごじゅう
throughout the afternoon