It's often used to form adjectives from nouns, indicating a connection to a particular thing or concept.
Examples:
* Tidal: relating to tides.
* Presidential: relating to a president.
* Bacterial: relating to bacteria.
* Aboriginal: relating to the original inhabitants of a place.
* Fungal: relating to fungi.
While "-ical" is more common, "-idal" is used in specific cases, particularly when it's used to create adjectives from words ending in "-ide."
Important Note: It's crucial to understand that "-idal" doesn't always have a direct literal meaning. Sometimes, it's used in a more figurative sense, emphasizing a resemblance or connection.