Idoneous is an adjective that means fit or proper.
Our word of the day comes almost directly from the Latin word idoneus (ee DOHN ee oos) and its meaning has remained much the same since evolving into English. When something is described as ideonous, we mean it fits a given need.
Visiting foreign countries can be a little uncomfortable because I never know the idoneous thing to say. It takes time to find the right phrase for the right occasion.