1 a [count] US : a small, thin package
I got two packets of broccoli seeds to plant this summer.
He puts two packets of sugar in his coffee.
Could you get me another packet of ketchup?
1 b [count] British : a package in which something is sold and bought
a packet [=(US) box] of crackers
a packet [=(US) pack] of cigarettes
2 a [count] US : a group of things that have been gathered together for a particular purpose and usually put into a container (such as a folder or a large envelope)
Your information packet includes a map and a schedule of all the events at the conference.
The senator's comments are included in his press packet. [=papers that give reporters official statements from public figures]
2 b [count] chiefly British : a small, thin package sent through the mail or delivered to a person
I received the packet of legal papers today.
3 [count] computers : an amount of information that is sent as a single unit from one computer to another over a network or the Internet
4 [singular] British, informal : a large amount of money
The furniture wasn’t expensive but we spent a packet on shipping charges.