介于 Traditional form: 介於 Pinyin (reading): jièyú Definitions: between intermediate to lie between Characters: 介 - agent, go-between, intermediary; to introduce; shell, armor 于 - at, in, on; to, from; alas! Traditional characters: 介 - agent, go-between, intermediary; to introduce; shell, armor 於 - at, in, on; to, from; alas!