Compound words have three forms
CLOSE- no space between the joined words.
Example: makeup
I put on makeup.
HYPHENATED- hyphen between the joined words
Example: make-up
I have to take a make-up exam.
OPEN- space between the joined words.
Example: make up
I have to make up that exam at my high school.
LETTER A COMPOUND WORDS
aboveboard
afterbirth
afterburner
afterglow
afterimage
afterlife
aftermath
afternoon
afterthought
airbag
airbrush
aircraft
airfield
airlift
airline
airmail
airman
airport
airship
airtight
allover
allspice
alongside
angelfish
another
anybody
anyhow
anyone
anyplace
anything
anytime
anyway
anywhere
applesauce
armchair
armhole
armpit
around
arrowhead
artwork
ashtray
authorship
awestruck