Today's word is, "guai (condition; state; health; convenience; manner)". It is written with a combination of the kanji characters "gu" and "ai". As stated, it is used for both condition and health. Here are some examples.
Kono kikai wa guai ga warui. --- This machine does not work well.
Konogoro karada no guai ga totemo ii. --- I feel very well recently.