How Do You Spell FORTHGO?
Pronunciation: [fˈɔːθɡə͡ʊ] (IPA) 
The word "forthgo" is spelled with the phoneme /θ/ (as in "thin") rather than /ð/ (as in "these"). This is because "go" is a root word with a voiced /ɡ/ sound, and adding the prefix "forth-" creates an unvoiced /θ/ sound to avoid creating a voiced consonant cluster. The IPA transcription of "forthgo" is /fɔrθɡoʊ/. So, the spelling of this word may seem unusual, but it follows the rules of English phonetics.
