The term 'definitely will' can be expressed in two different ways in a crossword puzzle. The first is 'SHALL, ' which is a five-letter word meaning 'to be obligated to do something.' The second is 'issureto, ' which is an eight-letter word meaning 'to be certain to do something.' Both words express the idea of certainty, but 'SHALL' implies a sense of obligation while 'issureto' implies a sense of assurance.