The word "bottommost" is correct and can be used in written English.
It can be used to refer to the lowest point or position of something, or to describe the furthest down position in a series. For example: "The bottommost shelf was the only one with enough space to store the boxes."
The bottommost, or aphotic, zone is the region of perpetual darkness that lies beneath the photic zone and includes most of the ocean waters.
If you think of the sciences as a tower, with one field resting on another until you reach, say, botany or physiology, then particle physics represents the bottommost floor.
With my husband, I visited her on weekends, walking up the stony road from our house, the bottommost of the villas, to the cottage where she lived, on her second son's property: three dark, beam-ceilinged rooms, set between the chapel and a crumbling brick alcove, where someone had propped a wooden sculling shell from the sixties.
The miners also carve out what Mr. Atkinson called "massive holes" in the riverbed, leaving piles of gravel just below the dredge, and uproot the insect colonies that are the bottommost link of the aquatic food chain.
The word "Discontinued" appeared next to the five bottommost items on a price sheet issued recently by Mercedes-Benz USA for its 2013 vehicles.
No, that's misleading; more likely it's the embodiment of my duties – not the least of which is talent – ignored by me and imprisoned in this bottommost oubliette of my mind".
One Eye's photograph is taped to the bottommost corner of the window, underneath a "hotchpotch of pleading eyes, foreheads worried into furry folds, tails frozen into a hopeful wag".
Imagine that: a great, warm, wet, abrasive tongue licking off skin after skin, down to the bottommost one, which starts to sprout shiny little animal hairs.
If you take an ice cube from the tray and look at the bottommost layer, it will be clear.
Under the Pataki administration, the Lower Manhattan Development Corporation proposed to disassemble the stairway, leaving some granite stair treads in their original location, but reoriented within the staircase to the lobby of Tower 2. The bottommost tread was to have been moved off and set into the memorial plaza.
It's the story of five improbably attractive young adults sharing a house (and their innermost thoughts) in Washington while they try to grab hold of the bottommost rung of the power ladder.
