The term 'put on weight' can be described by three crossword solutions: GAIN (4 letters), GAINED (6 letters), and FATTEN (6 letters). GAIN is a verb meaning to acquire or obtain something, usually through effort. GAINED is the past tense of the verb, indicating that something has been acquired or obtained. FATTEN is a verb meaning to make something bigger or thicker, usually referring to a person's body size. All three words refer to the same concept of increasing one's body weight.