word choice - What's the difference between "rigor" and "rigorousness"?

What's the difference between rigor and rigorousness?

Which should I use in the following?

Rigorousness and clarity are not synonymous in pedagogy.

Answer

The relationship between rigor and rigorousness is that rigor is similar in meaning to “severity” or “strictness”, but rigorousness is primarily “the abstract property of having to do with, or being inclined to, rigor”. As for which is best in your sentence, it simply comes down to which one you mean.

The suffixes -ous and -ness are productive, meaning they are used by English speakers as part of habits or “rules” for producing new words. These compound words, in the ears of English speakers, will generally mean what the individual parts mean.

The suffix -ous takes a noun X and creates an adjective X-ous which stands for “having X”, “full of X”, “having to do with X”, “doing X”, or “inclined to X”.¹

• avarice → avaricious (having/full of/having to do with/doing/inclined to avarice)


• beauty → beauteous (having/full of/having to do with/doing/inclined to beauty)


• cancer → cancerous (having/full of/having to do with/doing/inclined to cancer)

The suffix -ness can take an adjective Y and create a noun Y-ness which stands for the abstract action, quality, or state which Y has to do with.² You can think of this as converting a description of something to a property which it possesses.

• ripe → ripeness (abstract action, quality, or state property from ripe)


• strange → strangeness (abstract action, quality, or state property from strange)


• tight → tightness (abstract action, quality, or state property from tight)

As you might expect, then, when these productive suffixes are used together with a noun Z, the resulting compound Z-ous-ness will mean “the abstract action, quality or state of having/being full of/having to do with/doing/being inclined to Z”. You can think of this as converting a thing to an abstract property having to do with such a thing.

• mystery → mysteriousness (the abstract property of having to do with a mystery)


• number → numerousness (the abstract property of having a number)


• odor → odorousness (the abstract property of having an odor)

Because these habits or “rules” of new word production are instilled into the minds of English speakers, they will find it possible to make sense of words which are invented using this method, even when the combinations have never been seen before.

• santorum → santorumousness (the abstract property of having to do with santorum)

Such habits or “rules” are not, of course, the whole story. Once a new word is coined by compounding with suffixes and becomes a popular word, it is tossed and buffeted by the same social forces which cause all words to evolve in meaning. The compound may acquire unique connotations which do not wholly apply to its parts. A good dictionary will provide this information.