The word "kastner" can be spelled phonetically as /ˈkæstnər/. The first syllable "kas" is pronounced with a short "a" sound and the "s" sound is emphasized. The second syllable "tner" is pronounced with a short "e" sound followed by a silent "r." The spelling of the word follows typical English phonetics and pronunciation patterns. It is important to note that proper spelling is essential in communication to convey clear meaning and intent.