This is an odd word in that it is fairly common, however it's base word of ruth is rarely used. Isn't that odd?

What other words like that are common in English?

Just curious.

Couth (uncouth)

Erst (erstwhile)

Canard (That's a base canard!)

Prithee (pray thee, ask you)

Forsooth (indeed)

Zounds (wow!)

Gadzooks (wow!)

couth (uncouth)

erst (erstwhile)

canard (That's a base canard!)

prithee (pray thee, ask you)

forsooth (indeed)

zounds (wow!)

gadzooks (wow!)

I like the first one. I would call "uncouth" a common word but I don't recall the last time that I heard someone use the word "couth".

As for the other ones, I do not see them as the same. I cannot think of the last time that I heard anyone use (verbally or in writing) the other ones.

I like the first one. I would call "uncouth" a common word but I don't recall the last time that I heard someone use the word "couth".
There is no such word as "couth."

As for the other ones, I do not see them as the same. I cannot think of the last time that I heard anyone use (verbally or in writing) the other ones.
Most of them are used nowadays by gamers, depending on the game, of course.

Then there's troth, something that people plight.

Ok, so back to my question.

"ruth" is a legit word, but it's rarely used.

"ruthless" is a common word.

What other words are out there that are rarely used - where a prefix or suffix to the word is common?

Out of curiosity, how would one use the word 'ruth' in a sentence? -

(I looked it up in my dictionary, and it only has the description of the woman Ruth, from the bible. So I imagine 'ruthless' is used to describe a person or action that is considered 'without Ruth', as in without pity or compassion - traits that are tied to Ruth, but I'm not sure how to use the root word 'ruth' - and technically, should it be capitalized (Ruth), because it is actually a proper name? ) Love the English language - learn something new everyday!

- anyway, back to your question about root words not commonly used, what about 'assail'? - I hear the word 'assailant' all the time - but not 'assail'...

See also rue ("I'll forever rue the date I met you!") --

ruth

[rooth]
Noun
Archaic
1. pity; compassion
2. repentance; remorse
3. grief or distress
[from rewen to rue]

Origin: 1125–75; Middle English ruthe, reuthe.

—Synonyms
1. mercy, sympathy.

—Antonyms
1. cruelty.

The name Ruth means compassion, pity.

And just for fun --

Noun: a women's restroom. (See also john.) : Point me toward the ruth!

Dictionary of American Slang and Colloquial Expressions by Richard A. Spears. Fourth Edition. Copyright 2007. Published by McGraw Hill.