Answer:
Here are several singular nouns ending in "sh":
ash (The cigarette ash had grown longer.)
bash (We threw a big bash in his honor.)
bush (The rabbit ran under the bush.)
flash (The flash went off,
gash (There was a large gash on his forehead.)
hush (A hush fell over the room.)
lush (The character Meredith is a lush.)
lash (This mascara coats each lash separately.)
push (That confrontation gave him the push he needed.)
rash (The baby had a rash all over .)
rush (I get a rush from that first cup of coffee.)
stash (Do you know where he hides his stash?)
slash (There was a big slash in the middle of the painting.)
wash (When everything was taken into account, the trade was a wash.)
wish (Close your eyes and make a wish.)