1. Not allowable as a deduction

Antonym: deductible

• Ostmark
• ostomy
• Ostraciidae
• ostracise
• ostracism
• ostracize
• ostracod
• Ostracoda
• ostracoderm
• Ostracodermi
• Ostrava
• Ostrea
• Ostrea gigas
• Ostreidae
• ostrich
• ostrich fern
• Ostrogoth
• Ostrya
• Ostrya carpinifolia
• Ostrya virginiana
• Ostryopsis
• Ostwald
• Ostwald's theory of indicators
• Ostyak
• Ostyak-Samoyed