Explanation and Discussion
In American English
Compound Nouns
are sometimes hyphenated and sometimes not. No real rules exist but some
trends do. Below I have some of the major groups of words and their
generalities.
Up
Words
Some compound nouns ending in
"up"
are either solid or hyphenated. For
Example:
|
backup
|
blowup
|
breakup
|
buildup
|
checkup
|
cleanup
|
getup
|
holdup
|
letup
|
|
lineup
|
linkup
|
makeup
|
markup
|
paste-up
|
pileup
|
roundup
|
setup
|
slipup
|
|
smashup
|
warm-up
|
windup
|
call-up
|
catch-up
|
close-up
|
cover-up
|
flare-up
|
follow-up
|
|
foul-up
|
hang-up
|
jam-up
|
lead-up
|
mix-up
|
mock-up
|
runner-up
|
send-up
|
shake-up
|
|
sign-up
|
start-up
|
tie-up
|
toss-up
|
touch-up
|
wrap-up
|
write-up
|
Down
Words
Most compound nouns ending in
"down"
are solid. For Example:
|
breakdown
|
closedown
|
comedown
|
countdown
|
crackdown
|
letdown
|
lowdown
|
markdown
|
meltdown
|
|
rubdown
|
rundown
|
shakedown
|
showdown
|
shutdown
|
slowdown
|
sundown
|
turndown
|
dressing-down
|
|
put-down
|
sit-down
|
step-down
|
wind-down
|
write-down
|
|