shield / shēld/ • n. 1. a broad piece of metal or another suitable material, held by straps or a handle attached on one side, used as a protection against blows or missiles.2. something shaped like a shield, in particular: ∎  a police officer's badge. ∎  Heraldry a stylized representation of a shield used for displaying a coat of arms. ∎  Geol. a large rigid area of the earth's crust, typically of Precambrian rock, that has been unaffected by later orogenic episodes, e.g., the Canadian Shield.3. a person or thing providing protection: a protective coating of grease provides a shield against abrasive dirt. ∎  a protective plate or screen on machinery or equipment. ∎  a device or material that prevents or reduces the emission of light or other radiation. ∎ short for dress shield. ∎  a hard flat or convex part of an animal, esp. a shell.• v. [tr.] protect (someone or something) from a danger, risk, or unpleasant experience: he pulled the cap lower to shield his eyes from the glare these people have been completely shielded from economic forces. ∎  prevent from being seen: the rocks she sat behind shielded her from the lodge. ∎  enclose or screen (a piece of machinery) to protect the user. ∎  prevent or reduce the escape of sound, light, or other radiation from (something): uranium shutters shield the cobalt radioactive source.DERIVATIVES: shield·less adj.ORIGIN: Old English scild (noun), scildan (verb), of Germanic origin; related to Dutch schild and German Schild, from a base meaning ‘divide, separate.’

shield in the Middle Ages the armorial bearings of a knight were depicted on his shield; decorated shields, made for display rather than use, were often hung on walls in churches or other buildings as a memorial of a knight or noble. The word is recorded from Old English (in form scild) and is of Germanic origin; it comes ultimately from a base meaning ‘divide, separate’.

shield article of defensive armour; (fig.) protection, OE. sċ(i)eld = OS., OHG. scild (Du., G. schild), ON. skjǫldr, Goth. skildus — Gmc. *skelduz, prob. orig. ‘board’ and so f. base *skel-divide, separate (cf. SCALE1).
Hence vb. OE. sċeldan, sċildan.

shield
1. A tunnel borer consisting of a conventional shield with thrust rams and erector system. The cutter head and support are inside the shield. This type of machine is usually employed in soils or variable materials, e.g. a sand—rock—gravel sequence.

2. See CRATON.