Today's word is MODUS, which is a second-declension masculine noun.
Latin meaning and usage: The basic meaning of modus is a "measure" - a measure of size, length, circumference, or quantity. In poetry and music, it can refer to the rhythm or meter (note that the English word "meter" is based on the same metaphor). It can also have the connotation of the "right measure" or the "limit" of something. Most commonly, however, modus is used to refer to the "way" or "method," as in the Latin question word: quomodo, how?
Latin word formation: The word modus is extremely productive in Latin word formation. It gives rise to words like modernus, modero, modestus, modicus, modifico, modulor, and the many words in turn derived from those forms, as well as compound forms like commodus, etc. Also, in addition to quomodo, there are adverbs like admodum, dummodo, omnimodo, postmodo, quemadmodum, and tantummodo, along with many others.
English cognates and derivatives: Since there are so many Latin words formed from this root, there are likewise countless English derivates as well. The phrases modus operandi and modus vivendi are still used in English, as is the basic word "mode" and also "modicum" and "module." The word "mold" (in the sense of a form or shape) also comes from Latin modulus. The English word "model" comes from Latin modellus, a diminutive of modulus.
Here are some examples of today's word in Latin sayings and proverbs; for more information, see the page at the Scala Sapientiae, which also contains notes on some of the proverbs cited below, as well as additional proverbs:
Est modus in rebus.
Alii alio modo.
Faciam meo modo.
Omnis in modo est virtus.
Nescit amor habere modum.
Arma non servant modum.
Ordo et modus omnia breviora reddunt.
Omni in re modus est optimus.
Haud vivit ullus omnibus felix modis.
Nascimur uno modo, multis morimur.
Modum nescit ponere voluptas.
Suaviter in modo, fortiter in re.
Sine nunc meo me vivere modo.
Omnibus rebus modum adhibendum.
Pone irae frena modumque.
Pravo modo se in equo continere melius est, quam pulchro modo decidere.