UPON ONE'S GUARD
\əpˌɒn wˈɒnz ɡˈɑːd], \əpˌɒn wˈɒnz ɡˈɑːd], \ə_p_ˌɒ_n w_ˈɒ_n_z ɡ_ˈɑː_d]\
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By Princeton University
Word of the day
Ultraviolet Ray
- That portion electromagnetic spectrum immediately below visible range extending into x-ray frequencies. longer near-biotic vital necessary for endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-UV or abiotic extravital rays) viricidal, bactericidal, mutagenic, carcinogenic used as disinfectants.