What's "avid" mean and how it's used commonly?

Native speaker’s answer
Rebecca
To be an "avid [noun]" means to have a keen or special interest in that thing, usually a hobby of some kind. In this context, it means that Lord Sakai had a keen interest in fishing. Ex: I am an avid coffee drinker. Ex: My friend is an avid hiker, so she's always outdoors on the weekends.