What is the X in X-mas?
system of Romanized spelling for Chinese, 1963, from Chinese pinyin "to spell, to combine sounds into syllables," from pin "put together" + yin "sound, tone." Adopted officially by the People's Republic of China in 1958. Outside China gradually superseding the 19c. Wade-Giles system (Mao Tse-tung is Wade-Giles, Mao Zedong is pinyin).