  The usage of part-of-day nouns, such as 'night', and their time-specific
greetings ('good night'), varies across languages and cultures. We show the
possibilities that Twitter offers for studying the semantics of these terms and
its variability between countries. We mine a worldwide sample of multilingual
tweets with temporal greetings, and study how their frequencies vary in
relation with local time. The results provide insights into the semantics of
these temporal expressions and the cultural and sociological factors
influencing their usage.
