1) Archaeological feature 2) Hole 3) Post hole 
In archaeology a posthole is a cut feature used to hold a surface timber or stone. They are usually much deeper than they are wide although truncation may not make this apparent. Although the remains of the timber may survive most postholes are mainly recognisable as circular patches of darker earth when viewed in plan. Archaeologists can use thei...
[n] - a hole dug in the ground to hold a fence post
post hole noun a hole dug in the ground to hold a fence post