Falling behind is a term used to describe a situation in which someone or something is not keeping up with the progress of others. This can be seen in the crossword solutions for the term, such as 'LAGGING' (7 letters), 'LAG' (3 letters), 'SLOW' (4 letters), and 'losingground' (12 letters). All of these words imply that someone or something is not progressing at the same rate as others, and is thus falling behind.