orthography - Is semiannual one or two words? Or both? Or hyphenated?

I've looked on Google and StackExchange for the answer and am having no luck. This HAS to have been answered and asked before now... so I'm sorry in advance if this is a bad question or a repeat.

Answer

Semiannual is one word, without hyphens, according to Merriam-Webster. Semiannual