mailbox
a receptacle for receiving incoming mail
She checked the mailbox every morning for letters.
sandbox
a box or area filled with sand for children to play in; also a safe testing environment in computing
The children spent hours building sandcastles in the sandbox.
lunchbox
a container used to carry a packed meal, typically lunch
He packed a sandwich and apple into his lunchbox.
matchbox
a small box in which matches are sold or stored
She took a matchbox from the drawer to light the candle.
toolbox
a box in which tools are stored and carried
He grabbed his toolbox before heading out to fix the fence.
gearbox
a mechanical assembly of gears used to transmit power and change speed or torque
The mechanic inspected the gearbox for signs of wear.
jukebox
a coin-operated machine that plays selected music recordings
We chose a few old songs from the jukebox at the diner.
soapbox
a raised platform for public speaking; metaphorically, a strong expression of one's opinions
He climbed onto a soapbox in the park to address the crowd.
boxing
the sport or activity of fighting with the fists under rules
She took up boxing to improve her fitness and confidence.
boxful
the quantity that fills a box
He donated a boxful of books to the community library.