Understory

On the Vnder Story, tovvards the Garden, Let it be turned to a Grotta, or Place of Shade, or Eſtiuation.

Source: wiktionary

The two middle storeys of the towers are adorned with one tier of Corinthian pilasters in the style of Lord Carlisle's house at Castle Howard. The understorey is rustic.

Source: wiktionary

Elgin has vvhat in England are called piazzas, that run in many places on each ſide of the ſtreet. […] I approved much of ſuch ſtructures in a tovvn, on account of their conveniency in vvet vveather. Dr. Johnſon diſapproved of them, "becauſe (ſaid he) it makes the under ſtory of a houſe very dark, vvhich greatly over-balances the conveniency, vvhen it is conſidered hovv ſmall a part of the year it rains;[…]"

Source: wiktionary

Q. VVhat did you find? / A. I found in a cloſet in the under ſtorey of VVatt's houſe a dozen of ſpears.

Source: wiktionary