罗马 (Rome) +
化 (-ize) — literally 'Rome-ization,' since the Latin alphabet originated in Rome. For Mandarin,
拼音 (Pinyin) is now the international standard, but historical schemes
威妥玛 (Wade–Giles) and
注音 (Bopomofo) — strictly speaking, the latter isn't romanization since it uses native symbols — are still encountered.