an opening through a floor for light; a staircase or a chimneystack
wellhole in American English
(ˈwelˌhoul)
noun
1.
the shaft of a well
2.
a tall, narrow opening surrounded by walls, as a stairwell
Word origin
[1670–80; well2 + hole]This word is first recorded in the period 1670–80. Other words that entered Englishat around the same time include: guarantee, kink, plan, routine, slump