按照主贴中 ODE usage 所讲的“whereas prophecy is the correct spelling for the noun”,牛津的意思就是 prophesy 作名词属于拼写有误。
至于 Merriam-Webster 直接说 also prophesy,可以参考 Merriam-Webster’s Dictionary of English Usage (1994) 里的解释:
虽然 Vocabulary.com 中有如下这段话:
Until 1700, the noun and the verb were spelled the same. However, the differentiated spelling may be disappearing already. Garner's Modern American Usage notes that prophesy for prophecy is at stage 3 of language change: it's common even among educated speakers and writers.
但它也是根据 Garner's Modern American Usage 进一步给出的论断,其实 Garner's Modern American Usage (2016) 书中依旧将其定性为 misspelled,即拼写有误。
而 Vocabulary.com 的那句 "it's common..." 也没有把 Garner 的 language-change index Stage 3 意思表达完整。按 Garner 的标准,Stage 3 指 The form becomes commonplace even among many well-educated people but is still avoided in careful usage.