"Free balloon" is a phrase commonly used to describe a balloon given away for free. However, there are many synonyms that can be used to spice up your writing and make it more interesting. Some synonyms for "free balloon" include "complimentary balloon," "gift balloon," "gratis balloon," "no-cost balloon," "donated balloon," and "giveaway balloon." Each of these synonyms offers a different shade of meaning and can be used depending on the context and tone of your writing. Experiment with different synonyms to add variety and flair to your language.