Either a medieval compendium of animals, sometimes assigning a moral lesson to each or, in other contexts, the general study of animals in a medieval setting.
"He was a master bestiarist, that is to say he was an expert in the field of bestiary."
A book usually containing mythical creatures and information about them. Mostly used in olden times (when people thought dragons existed). It could have gryphons, dragons, manticores, unicorns, pegasus, sea monsters, and much more. It could also be a document of non-mythical creatures such as foxes, deer, wolves, hedgehogs, and so on.
Person 1: I'm making beastiary about these cool animals I thought up of.
Pajama casual is a term used when working from home and preparing for a video conference. All business above the waist and your pajama pants down below.
We have a Zoom meeting in a few minutes and I’ll probably go pajama casual.