The term 'moves erratically' can be described by the crossword solutions of 'flits, ' 'ZIGS, ' and 'zags.' Flits is a verb meaning to move quickly and lightly, often in an irregular or unpredictable manner. Zigging and zagging are both verbs that refer to moving in a zigzag pattern, which is a pattern of alternating between two directions. All three words describe movement that is not steady or predictable.