Today's word is LONGUS, which is a regular first-second declension adjective.
Latin meaning and usage: The basic meaning of the Latin word is "long," but note that it can also mean "tall," as well as "distant." It can also refer to something "long-lasting." As often an adjective that refers to space can also be applied to time!
Latin word formation: There is an adverbial form, longe, meaning "a long way off, at a distance" and also "for a long time." There are many words derived from this root in Latin, such as the adjective longinquus, as well as compounds such as longaevus. There is also an abstract noun, longitudo. Don't forget the intensive forms, too: perlongus and perlonginquus, too.
English cognates and derivatives: Of course, we have English "long" as well as "longitude" and "longevity," along with comopunds such as "oblong," "prolong" and "elongation." We get "purloin" from this root via the Old French porloigner and "lunge" via the Old French alongier. (But note that "belong" is not from Latin; it is from a Germanic root, which you can see in German belangen.)
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:
Longae regum manus.
Nullus agenti dies longus est.
Nox tibi longa venit nec reditura dies.
Vive tibi et longe nomina magna fuge.
Legis manus longa.
Longa est vita, si plena est.
Alta a longe cognoscuntur.
Vita beatior non fit, si longior.
Vita, si scias uti, longa est.
Ars longa, vita brevis.
Breve tempus aetatis, satis longum ad bene vivendum.
Brevis ipsa vita est, sed malis fit longior.
O vita misero longa, felici brevis!
Vita misero longa, felici brevis.
Longa via est: propera.
Nil agenti dies longus est.
Mutat via longa puellas.
Brevis via per exempla, longa per praecepta.
Recede longius, et ride.
Sapientia longe praestat divitiis.