According to Merriam-Webster.com, the top word for Valentine's Day is romantic. The word resulted after people living in Rome became famous for their love stories, known as romances. It is a classic word that conveys what people long for in a relationship.
Another ideal word for Valentine's day is amour, which is the French word for love. In 2010, the word was voted as the most romantic in the world. Other typically less popular words include passion, adoration, admiration and infatuation, all of which can describe the type of love two people feel for one another.
Words to describe romantic interest could include for males: handsome, sexy, devilish, tantalizing, delicious, sweet, and compassionate and for females: divine, heavenly, goddess-like, perfect, sensuous, scrumptious and lovely.
The word choice is also dependent upon the mood you are trying to create. Expressing new-found love for a friend elicits a very different set of words than for a long-time partner or spouse. When discussing friends, use words like care, respect and admire to convey a sense of friendship and not love. On the other hand, when dealing with someone you truly love, be open and admit your romantic feelings using words like adoring, longing, and desiring.