The term ‘perfectest’ is often considered nonstandard or informal, although it can be found in some contexts. It is generally used to convey the idea of something being the most perfect among several options.
In standard English, the word ‘perfect’ already implies a state of being without flaws or defects. Thus, the superlative form ‘perfectest’ might seem unnecessary, as ‘most perfect’ is the more widely accepted structure. However, in some dialects or creative writings, you might encounter ‘perfectest’ used for emphasis or stylistic effect.
In summary, while ‘perfectest’ might not be universally recognized in formal contexts, it can be understood in certain situations. Nonetheless, it’s often clearer and more grammatically sound to use ‘most perfect’ when expressing this idea.