Today's word is MUNDUS, which is a second-declension masculine noun.
Latin meaning and usage: The basic meaning of Latin mundus is "world," in the sense of the whole world, the universe or cosmos. This usage derives metaphorically from the meaning of mundus as "decorations" or "dress." You can see a similar metaphorical range of meaning in the Greek word κόσμος, which gives us both "cosmetics" and "cosmos" in English.
Latin word formation: There is also an adjective mundus (-a, -um) which means "clean" or "neat." So, whenever you meet up with a form of Latin mundus you have to ponder whether you have encountered the noun or the adjective; only context can give you that answer. There are two adjectives, mundialis and mundanus, with its compounds in turn: extramundanus, ultramundanus, etc. There are also other compound adjectives like mundipotens, mundivagus etc.
English cognates and derivatives: We get English "mundane" from this root and, via French, "beaumonde" and "demi-monde."
Here are some examples of today's word in Latin sayings and proverbs; for more examples, see the page at the Scala Sapientiae, which also contains notes on some of the proverbs cited below:
Patria mea totus hic mundus est.
Mundus non capit duos soles.
Sol oculus mundi.
Amor mundum fecit.
Non sibi, sed mundo.
Vos estis lumen mundi.
Vos estis lux mundi.
Vincere cor proprium plus est quam vincere mundum.
Roma caput mundi.
Numeri regunt mundum.
Cives mundi omnes sumus.
Civis totius mundi sum.
Sic transit gloria mundi.
Mundus ipse est ingens deorum omnium templum.
O quam cito transit gloria mundi!
Homo mundus minor.
Sol oculus mundi, princeps oculus multitudinis
Quam parva sapientia regitur mundus!
Qui amat mundum praesentem, sequitur rem fugientem.