Healthier, healthiest. Healthy is an adjective, which means healthy; Robust; Healthy. For most adjectives, the comparative degree is formed by adding -er at the end. However, for words with -y at the end of adjectives or y at the end of consonants, y should be changed to I, and -er should be added to form a comparative degree, and the highest level should be composed of -est at the end of words; The superlative is the same as the comparative. If an adjective ends with -y, or a word ends with a consonant plus y, you need to change y to I plus -est. So the comparative level of health is healthy, and the highest level is healthy.