joist

A piece of timber or steel laid horizontally, or nearly so, to which the planks of the floor, or the laths or furring strips of a ceiling, are nailed.

[…] a Family was infected there, in so terrible a Manner that every one of the House died; the last Person lay dead on the Floor, and as it is supposed, had laid her self all along to die just before the Fire; the Fire, it seems had fallen from its Place, being of Wood, and had taken hold of the Boards and the Joists they lay on, and burnt as far as just to the Body, but had not taken hold of the dead Body […]

There are generally forty-two teeth in all; in old whales, much worn down, but undecayed; nor filled after our artificial fashion. The jaw is afterwards sawn into slabs, and piled away like joists for building houses.

To fit or furnish with joists.

The floors are joisted with sapling tree trunks, and the flooring itself is made of bark, split and pounded flat into strips. No attempt is made either to fasten or join the strips of flooring.