Of keen appetite can be replaced with a variety of synonyms to add more variety to your writing. Here are ten alternatives: ravenous, voracious, famished, hungry, eager, desirous, craving, yearning, athirst, and insatiable. Each of these words conveys a strong sense of hunger or desire for something. They can be used in various contexts, from describing a person's hunger for food to their hunger for success or knowledge. By incorporating these synonyms into your writing, you can add more depth and nuance to your descriptions and create a richer, more engaging reading experience for your audience.