What is the greek word for rare?

There isn't one single perfect Greek word for "rare" as the meaning depends on the context. Here are a few options, depending on what you mean by "rare":

* Σπάνιος (spánios): This is the most common and versatile option. It refers to something that is infrequent, uncommon, or seldom encountered. This is probably the closest overall translation.

* Αφθονία (afthonía): This actually means "abundance" or "plenty," so its opposite could be used for "rare" – the lack of abundance. You might use a phrase like *η έλλειψη αφθονίας* (i ēlleipsē afthonías) meaning "the lack of abundance."

* Πρόσφατος (prósphatos): This means "recent" or "fresh," so it could be used to describe a rare instance of something *recently* happening.

* Ξενικός (xenikós): This means "foreign" or "strange," and could be used to describe something rare or unusual *because* it's from somewhere else.

To choose the best word, you need to specify what kind of rarity you're describing. For most situations, σπάνιος (spánios) is the safest and most appropriate choice.