dot 1 S2 / dɒt $ dɑt / 名词 [可数名词]

1 a small round mark or spot :

a pattern of dots

2 on the dot informal exactly on time or at a particular time :

I’ll be there on the dot.

at three o’clock/seven thirty etc on the dot (= at exactly 3:00/7:30 etc )

Mr Green arrived at six on the dot .

3 something that looks like a small spot because it is so far away :

The plane was just a dot on the horizon .

4 a short sound or flash of light used when sending messages by Morse code → dash

→ the year dot at year ( 13 )