more sincere (sincerer), the most sincere (sincerest)
The comparative degree of sincere is more sincere.
Comparative: more sincere Superlative: most sincere
The comparative degree of "deliberate" is "more deliberate."
The comparative degree of the word "honest" is "more honest."
The superlative degree of selfish is "most selfish", and the comparative degree is "more selfish".
nobler, noblest
The superlative degree of word sincere can be most sincere ,or sincerest according to its use in the sentence.
more sincere -- James is more sincere than Melissa most sincere -- James is the most sincere person I know.
Comparative: more sincere Superlative: most sincere
Teapot is a noun and, as such, does not have a comparative degree.
"Less" is the comparative degree of little.
The comparative degree is bigger.
The comparative degree is wider.
Thriftier is the comparative degree of thrifty.
The superlative degree of word sincere can be most sincere ,or sincerest according to its use in the sentence.
"Speed" is a noun and a verb and, as such, does not have a comparative degree. The comparative of the adjective speedy is speedier.
"Less" is the comparative degree of little. The superlative degree is least.
The way you have it spelled in your question is as good as any - it's not really a word. Sincere is a word who's comparative and superlative are : more sincere, most sincere.