The 二 (two) component represents the meaning "second" and also indicates the sound. The 欠 (deficient) represents the meaning "secondary" or "substandard".
Alludes to the meaning "second-class" or "inferior".
Character Evolution
Oracle Bone~1250-1000 BCOracle Bone~1250-1000 BCBronzeEarly Western Zhou~1000 BCBronzeMid Western Zhou~900 BCBronzeLate Spring and Autumn~500 BCBronzeLate Spring and Autumn~500 BCSealXin9-23 ADSealShuowen~100 ADSealShuowen~100 ADClericalQin221-206 BCClericalQin221-206 BCClericalQin221-206 BCClericalEastern Han25-220 ADClericalEastern Han25-220 ADRegularModern