The word "exosmic" refers to a process where a substance is released into the atmosphere. The spelling of this word can be explained using IPA phonetic transcription. The prefix "exo-" means "outward" or "external", while "-smic" relates to a certain type of energy or radiation. Therefore, the word is spelled with the letter "x" to indicate the combination of the two sounds, as in "ek-soz-mik". It is important to spell words accurately to ensure clear communication and understanding.