Any knot tied in such a way as to form one non-cinching loop around one or more body parts or objects.
The terminology “single column” is misleading as a Singe Column Tie can be tied around more than one Column. For instance a single column tie around both wrists to start a Takatekote 高手小手. This is why it is easier to recognize it by the number of loops it forms.
Single Column Tie is often abbreviated as SCT and/or shortened to simply “single column.”
Single Column Ties are most commonly used to anchor rope to start a tie, to attach an upline to the body , or to attach an upline to a harness. A SCT can also be tied in line or in the bight to attach to a column after a rope has already been anchored. A true in line SCT is different from a Hojo Cuff as the Hojo Cuff can cinch.
There are many versions and adaptations of knots that qualify as a Single Column. Riggers often debate the usefulness and faults of various Single Column Ties.
This table of various Single Column Ties has links to their individual dictionary pages as well as a quick reference to their properties.