noun
vertical pit; shaft
A hole or shaft that goes straight down, as opposed to a horizontal tunnel. Often used in archaeology (竪穴住居) and mining.
遺跡から竪穴住居の跡が見つかった。
Remains of pit dwellings were found at the archaeological site.
鉱山の竪穴はとても深い。
The mine shaft is very deep.
横穴 means a horizontal hole or tunnel, while 竪穴 is a vertical pit or shaft.
Compound of 竪 (tate, 'vertical') and 穴 (ana, 'hole').