Eat  —v. (past ate; past part. Eaten) 1 a take into the mouth, chew, and swallow (food). B consume food; take a meal. C devour (eaten by a lion). 2 (foll. By away, at, into) a destroy gradually, esp. By corrosion, disease, etc. B begin to consume or diminish (resources etc.). 3 colloq. Trouble, vex (what's eating you?). —n. (in pl.) Colloq. Food.  eat one's heart out suffer from excessive longing or envy. Eat out have a meal away from home, esp. In a restaurant. Eat up 1 eat completely.