backbone
the main support, strength, or spine
Her determination became the backbone of the movement.
background
circumstances or history behind a person or situation; setting behind a subject
His background in engineering helped on the project.
backpack
a bag carried on the back; to carry something in a backpack
She packed her textbooks into a backpack before leaving.
backfire
to produce an outcome opposite to what was intended; an unintended negative result
The advertising campaign backfired and cost them customers.
backtrack
to go back over one's previous route or to reverse an earlier position
When he realized the error, he had to backtrack and fix it.
backlash
a strong adverse reaction by a large number of people
The policy change provoked a widespread backlash.
comeback
a return to a former good position or popularity
After years away, the actor made a successful comeback.
throwback
a reversion to an earlier type or characteristic; something reminiscent of the past
The car's design is a throwback to the 1950s.
backspace
a key that deletes the character before the cursor; to delete using that key
If you make a mistake, press backspace to erase it.
backward
toward the back; moving or directed to the rear; less developed or slow to progress
He took a backward step when the loud noise startled him.