Candor vs Candid

Many may confuse the two words, ‘candor’ and ‘candid.’ The reason, for such, is because they have very close meanings. However, there should be a clear distinction between them, much more that they are two different word types.
Foremost, ‘candor’ is identified as a noun. ‘Candor’ is synonymous to the word, brilliance, unstained purity, fairness, unreserved honesty, forthrightness and sincere expression among others. For example, ‘She spoke about gender equality to the public with lots of candor’ or ‘His speech is full of candor.’
With regard to the origin of the word, grammarians say that candor has both Latin and French roots. It was derived from the words, ‘candeur’ (French) and ‘candor’ (Latin) back in the 14th century.
On the contrary, ‘candid’ is an adjective. But in some cases, people use this word informally, to refer to a candid type of picture, which makes it look like a noun like in the sentence; ‘He took a candid with us using his new DSLR camera.’ ‘Candid’ has lots of synonyms like direct, frank, forthright, honest, unreserved and many other more.
Basically, ‘candid’ describes something that is free from prejudice, malice and bias. Like candor, the expression is also sincere and honest. Some good examples of sentences that use the word ‘candid’ are ‘She was undoubtedly candid about her past life’ or ‘He told us his candid opinion about the current situation.’
‘Candid’ also has a French root ‘candide’ and Latin background ‘candidus’ that literally means white or bright. It is said that the word was first used sometime in the 1600s.
Perhaps, the reason why many mistakenly use the word ‘candid’ for ‘candor’ or vice versa is because ‘candor’ is synonymous to ‘candidness.’ However, if you look at these two words closely ‘candidness’ is in the form of an abstract noun. Hence, you can substitute the word ‘candor’ with ‘candidness’ in some sentences, but never use ‘candid’ for the same purpose, which may make your sentence grammatically incorrect.
Some may also ask if you can use the two words altogether in one simple sentence. The answer is yes, like, ‘They just seem to have a candid candor.’ This may look and sound awkward but still, this is grammatically correct, just as when you say, ‘He was filled with happy happiness’ although sentences like this are rarely used or doesn’t make much sense.

1. Candor is a noun, while candid is predominantly an adjective.
2. Candor has earlier roots compared to candid.