“SUBSISTS” is a valid word. — 10 points Scrabble

suitsa set of garments (usually including a jacket and trousers or skirt) for outerwear all of the same fabric and color
bustsa complete failure
stubsa short piece remaining on a trunk or stem where a branch is lost
situs

suita set of garments (usually including a jacket and trousers or skirt) for outerwear all of the same fabric and color
busta complete failure
bitsa small piece or quantity of something
sitsbe seated
subsa large sandwich made of a long crusty roll split lengthwise and filled with meats and cheese (and tomato and onion and lettuce and condiments); different names are used in different sections of the United States
buts
stuba short piece remaining on a trunk or stem where a branch is lost
tubsa relatively large open container that you fill with water and use to wash the body
susstype genus of the Suidae
bussthe act of caressing with the lips (or an instance thereof)
tuis
sibsa person's brother or sister

butand nothing more
bita small piece or quantity of something
sitbe seated
its
busa vehicle carrying many passengers; used for public transport
sisa female person who has the same parents as another person
tuba relatively large open container that you fill with water and use to wash the body
suba large sandwich made of a long crusty roll split lengthwise and filled with meats and cheese (and tomato and onion and lettuce and condiments); different names are used in different sections of the United States
tis
tui
bis
siba person's brother or sister
uts

itthe branch of engineering that deals with the use of computers and telecommunications to retrieve and store and transmit information
ishave the quality of being; (copula, used with an adjective or a predicate noun)
usNorth American republic containing 50 states - 48 conterminous states in North America plus Alaska in northwest North America and the Hawaiian Islands in the Pacific Ocean; achieved independence in 1776
sia tetravalent nonmetallic element; next to oxygen it is the most abundant element in the earth's crust; occurs in clay and feldspar and granite and quartz and sand; used as a semiconductor in transistors
bia heavy brittle diamagnetic trivalent metallic element (resembles arsenic and antimony chemically); usually recovered as a by-product from ores of other metals
tia light strong grey lustrous corrosion-resistant metallic element used in strong lightweight alloys (as for airplane parts); the main sources are rutile and ilmenite
utthe local time at the 0 meridian passing through Greenwich, England; it is the same everywhere

SUBSISTS