Platonic is a word with many meanings. In the aromantic community, platonic is commonly used to denote feelings or relationships which are not romantic in nature, such as friendships. Outside the aromantic community, platonic may be used to mean nonromantic, nonsexual, or both, owing to the fact that for many people, romance and sex are interrelated. The term "platonic" is derived from the name of the Greek philosopher Plato. A more precise Greek word would be philia, the love between friends.
Queerplatonic is related to and can be considered a subcategory of platonic.