The term 'Call the Whole Thing Off' is a phrase that originated from a popular song by George Gershwin and Ira Gershwin. The two crossword solutions for this term are 'Lets' (4 letters) and 'Endit' (5 letters). 'Lets' is an informal way of saying 'let us' and 'Endit' is a verb meaning to bring something to an end or conclusion. Together, these two words suggest that the speaker is suggesting to end the situation or conversation.