The definition of macho is an overly assertive man who shows excessive pride in his manliness.(adjective)
Walking around flexing your big muscles all the time and talking about what a big strong man you are is an example of macho behavior.
See macho in Webster's New World College Dictionary
noun pl. machos
Origin: Sp < Port, ult. < L masculus, masculine
See macho in American Heritage Dictionary 4
Origin: Spanish, male
Origin: , from Latin masculus; see masculine.
noun pl. MA·CHOs
Origin: m(assive) a(strophysical) c(ompact) h(alo) o(bject).
Learn more about macho