1 buck /ˈbʌk/ noun
plural bucks
1 buck
plural bucks
Learner's definition of BUCK
: dollar
: money
: a male animal (such as a male deer) compare doe
informal : man

bang for the/your buck

see 2bang

look/feel like a million bucks

see million

pass the buck

: to avoid a responsibility by giving it to someone else

the buck stops here

◊ Expressions like the buck stops here are used to say that you accept a responsibility and will not try to give it to someone else.
2 buck /ˈbʌk/ verb
bucks; bucked; bucking
2 buck
bucks; bucked; bucking
Learner's definition of BUCK
[no object] of a horse : to jump violently into the air with the back bent upward sometimes used figuratively
[+ object] : to oppose or resist (something or someone)

buck for

[phrasal verb]
buck for (something) US, informal
: to try very hard or work very hard to get (something)

buck up

[phrasal verb] informal
: to become happier or more confident
buck (someone) up or buck up (someone) : to cause (someone) to be happier or more confident : to cheer up (someone)