Deceptious is a word that is not commonly used, and many people are unfamiliar with its spelling. The word is spelled dɪˈsɛpʃəs, with the IPA phonetic transcription indicating that the "cep" sound is pronounced like "sep." The meaning of deceptious is deceitful or misleading, and it can be used to describe behavior or appearances that are not what they seem. While the word may not be commonly used, it can be a useful tool for accurately describing situations where things are not as they appear.
There is no word deceptious in standard English. It is possible that you are referring to the word deceptive instead. The etymology of the word deceptive comes from the Latin word deceptivus, which is the past participle of decipere, meaning to deceive.