"灌输" is formed from the character "灌", meaning to pour or irrigate, which itself combines the water radical (氵) with the component "雚" indicating sound and contributing to the meaning of flowing, and the character "输", meaning to convey or transport, which combines the cart radical (车) with "俞" for sound. Their semantic merger yields the compound word's meaning of instilling ideas or knowledge, metaphorically blending pouring with conveying.