Per Answers.com, to retreat, hang (back) or fall (behind) in movement, progress, development, etc.
Synonyms: http://www.answers.com/topic/fall-back-and-forward, http://www.answers.com/topic/lose, http://www.answers.com/topic/drop-off-wordnet, http://www.answers.com/topic/recede, http://www.answers.com/topic/lag, http://www.answers.com/topic/dawdle, http://www.answers.com/topic/fall-back-and-forward
because it derived from Latin word
the forces behind the fall of the UssR were the waffles the pancakes the pizzas and the all the chubby guys in the world!
You injure your vital coccyx.
Does Adamo mean to fall in love with?
What does the MS mean behind a counselors name.
Sorry, you cant.
because they fall behind in school work
NikkiRich Fall 2013 Fashion Show Behind the Scenes - 2013 was released on: USA: 11 March 2013
About 80% of people who fall asleep behind the wheel die.
Fall can mean one of the 4 seasons of the year. Fall can also mean tripping and landing on the ground. Fall can also mean someone doing something that makes them look bad or foolish, as in " a fall from grace."
"Lagging behind" means being slower or falling behind others in progress, development, or achievement. It implies not keeping up with the pace or standards set by others.
If by 'behind' you mean underneath, it's the asthenosphere .