surd：无道理的，[数]不尽根的，清音的

来源于拉丁语形容词surdus, -a, -um(聋,无声的)。

• instigation
• instigator
• instill
• instinct
• instinctive
• institute
• institution
• institutional
• institutionalize
• instruct
• instruction
• instructor
• instrument
• instrumental
• instrumentalist
• instrumentation
• insubordination
• insubstantial
• insufferable
• insufficient
• insular
• insularity
• insulate
• insulating
• insulation