To be big on something is to have a strong liking or preference for it. Some synonyms for this phrase are to be fond of, to be enthusiastic about, to be passionate about, to be keen on, to be into, to be crazy about, to be hooked on, or to be a fan of. A person who is big on something may also be described as an aficionado, an admirer, a devotee, a buff, or a lover of that particular thing. Whether it's a hobby, a sport, or a pastime, being big on something is a great way to express oneself and enjoy life to the fullest.