Ceiling
noun
The heaven well is the well that goes up into the heavens. This is above you, and it is a ceiling. Maybe the "well" part is referring to the chimney that goes up through the ceiling to the heavens when you look up in a super old house?
てんじょう
This is a jukugo word that uses the on'yomi readings of the kanji. You didn't learn that reading for 井, so we've got a mnemonic to help you out with that. Just note that the on'yomi for 井 isn't actually じょう, but rather しょう, it just ends up getting rendaku'd here! Fixing up ceilings is a tricky task, but you've got just the man for it: Joe (じょう). Your local farmhand that does it all, nothing is too tricky or out of reach for him, you're starting to think that this man can do just about anything. What a handy person to have around.
天井にクモがいる！
There is a spider on the ceiling!
このプランター、天井からつるしたいんだ。
I want to hang this planter from the ceiling.
どうやらあの日が相場の天井だったようだね。
It seems like that day was the ceiling for the stock market.