One of the mysteries of the English language finally explained.
noun
1‘a cricket ball’
sphere, globe, orb, globule, spherule, spheroid, ovoid
drop, droplet, bead
informal pill
2‘a musket ball’
bullet, projectile, shot, pellet, slug, lead
noun
1‘a fancy-dress ball’
dance, dinner dance, masked ball, masquerade, tea dance
North American hoedown, prom
thé dansant
informal hop, disco, bop
Phrases
‘if you are really on the ball, you'll guess the killer’
alert, quick-witted, sharp, bright, quick, keen, perceptive, wide awake, responsive, agile, acute, astute
on one's toes, quick off the mark, quick on the uptake, all there, with it, bright-eyed and bushy-tailed
whip-smart
slow
have a good time, have a great time, have fun, have the time of one's life
enjoy oneself
let one's hair down, whoop it up, have a fling, make whoopee, push the boat out, paint the town red, live it up