How Do You Spell THIR?
Pronunciation: [θˈɜː] (IPA) 
The word "thir" has an unusual spelling due to the way it is pronounced. The IPA phonetic transcription for this word is /θər/. The initial sound /θ/ is the voiceless dental fricative, which is produced when the tongue is placed between the teeth and air is forced out. The following vowel sound is pronounced as a short "i" sound /ɪ/, which is followed by the consonant sound /r/. The spelling of this word can be confusing for those who are accustomed to traditional English pronunciation rules.
