A dictionary of Confusable Phrases: More Than 10,000 Idioms and Collocations

Note: 
The expression is not antonymous in meaning to the
phrase not before its time— used of smth. that should have been
done long ago: At last they are installing electric light in the
main streets, and not before its time.
ahead of time • before time
ahead of time —(usually showing approval) earlier than ex-
pected: The homework was finished ahead of time so he went
out to play.
before time —prematurely; before the due or expected time:
So far was prepunctuality carried, that Her Majesty was ten
minutes before time.
aim at something • aim for something
aim at something —
1
. point the weapon or object in the di-
rection of smth.: He aimed at the far wall and squeezed the
trigger. 2. plan or hope to achieve smth.: We are now aiming
at a higher production level.
aim for something — = aim at something 2: For most people,
aiming for a higher position at once is the key to job search
success.
air boat • inflatable boat
air boat—
1
. a seaplane with a boatlike fuselage: This class
of seaplanes, variously termed “flying-boat” and “air-boat,”
consists essentially of a long boat-shaped hull, wherein the
passengers’ seats are contained. 2. a shallow-draft boat driven
by an airplane propeller: A Pandora’s Box is opening to release
a flood of airboats on the long-suffering landscape of crowded
Southern Ontario.
inflatable boat—an air-filled rubber boat (for use in an
emergency, etc.): The crewmen had to be pulled from the
freez ing water by colleagues in an inflatable boat.
air gun • air gunner
air gun —a gun in which compressed air is used to propel
the charge: Darned if he didn’t up with this here air gun and
plunk me with a buckshot it carried.
air gunner —an aircrew member whose job is to operate a
gun: Too old for piloting he became an air gunner with 235
Squadron Coastal Command.