Exceptions to the generalisation that Chinese characters represent monosyllables
(This is a side note to the page The Chinese Writing System)
Although Chinese characters almost invariably represent monosyllabic forms (each character represents a single syllable), there are a few rare exceptions.
1. At one stage polysyllabic characters were created to represent foreign weights and measures.
For example, li2-mi3 'centimetre', hao2-ke4, 'milligram', qian1-ke4, 'kilogram', qian1-wa3 'kilowatt', etc.
These characters are no longer used, at least in Mainland China.