The Collaborative International Dictionary
Indention \In*den"tion\, n. (Print.) Same as Indentation, 4.
Douglas Harper's Etymology Dictionary
1763, formed irregularly from indent + -ation. It could be a useful word if it split with indentation the two senses (relating to margins and to dents) of that word, but indention, too, is used in both.
Wiktionary
n. The act of indenting a line of text by including blank space at the beginning
Usage examples of "indention".
Most of the rocks he’d removed had come from the center of the kiva and now an indention in the floor was visible.
Her thumb moved slowly, in sensuous circles until it pressed into the small indention there.
It ran in rivulets down her waist, a small amount pooled in the tiny indention of her belly button and her thighs glistened with it and the added mixture of thick juice that accumulated from her bare, flushed pussy.
A dark hole, and above it a smaller indention where the torch holder had been yanked from the wall.
The corporal had been looking for Jones's dog, and he saw the shape of a man standing in the small indention where the cabin and Quonset hut came together.