This word is used in Psalms 84:10 (RSV marg., "stand at the threshold of," etc.), but there it signifies properly "sitting at the threshold in the house of God." The psalmist means that he would rather stand at the door of God's house and merely look in, than dwell in houses where iniquity prevailed.
Persons were appointed to keep the street door leading into the interior of the house (John 18:16,17; Acts 12:13). Sometimes females held this post.
These dictionary topics are from M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition, published by Thomas Nelson, 1897. Public Domain, copy freely.
Easton, Matthew George. "Entry for 'Door-keeper'". "Easton's Bible Dictionary".