shield (n.) Look up shield at Dictionary.com
Old English scield, scild "shield; protector, defense," literally "board," from Proto-Germanic *skelduz (cognates: Old Norse skjöldr, Old Saxon skild, Middle Dutch scilt, Dutch schild, German Schild, Gothic skildus), from *skel- "divide, split, separate," from PIE root *(s)kel- (1) "to cut" (see scale (n.1)). Perhaps the notion is of a flat piece of wood made by splitting a log. Shield volcano (1911) translates German Schildvulkan (1910). Plate tectonics sense is from 1906, translating Suess (1888).
shield (v.) Look up shield at Dictionary.com
Old English gescildan, from the root of shield (n.). Related: Shielded; shielding. Compare German scilden.