域 and 或 don't sound similar in modern Mandarin due to historical phonetic changes. They were more similar
in older Chinese.
Character Evolution
BronzeEarly Western Zhou~1000 BCBronzeEarly Western Zhou~1000 BCBronzeEarly Western Zhou~1000 BCBronzeEarly Western Zhou~1000 BCBronzeLate Western Zhou~800 BCBronzeLate Western Zhou~800 BCBronzeMid Spring and Autumn~600 BCBronzeLate Warring States~250 BCSealWarring States (Chu)475-221 BCSealWarring States (Chu)475-221 BCSealShuowen~100 ADSealShuowen~100 ADClericalQin221-206 BCClericalWestern Han202 BC-9 ADClericalWestern Han202 BC-9 ADClericalEastern Han25-220 ADClericalEastern Han25-220 ADClericalWestern Jin266-316 ADRegularModern