Word choice is a crucial aspect of communication. The word "callidity" refers to the quality of being shrewd or cunning in social or business interactions. While it is a useful term, there are several other synonyms that can be used to convey the same idea. Smartness, astuteness, canniness, and acumen are all great alternatives to "callidity." If you want to communicate the same idea of being shrewd but with a slightly different tone, consider using words like craftiness, guile, or slyness. Ultimately, having a rich vocabulary allows you to express yourself more precisely and can help you connect more effectively with your audience.