The word "unperceivably" is spelled with the prefix "un-" meaning "not," the root "perceive" meaning "to become aware of," and the suffix "-ably" meaning "in a manner that can be done." The phonetic transcription of this word is /ʌnpɚˈsivəbli/. This word may not be commonly used in everyday language, but it represents a correct combination of English language roots and suffixes to form a new word.
The word unperceivably is formed from the prefix un- meaning not, the root word perceive meaning to become aware of something through the senses, and the suffix -ably indicating the possibility or capability of something.
In terms of etymology, perceive comes from the Latin word percipere, which means to seize, perceive, or understand. The Latin word is a combination of per meaning through and capere meaning to take or to grasp.