intelligence quotient 
(abbreviation IQ)
noun
A number representing a person’s reasoning ability (measured using problem-solving tests) as compared to the statistical norm or average for their age, taken as 100.Intelligence tests usually give a score expressed as an intelligence quotient or IQ....
- The intelligence quotient averaged one hundred and fifty points, the highest among them excelling to over one hundred and eighty, in some few cases.
- The children were of average intelligence quotient and aged 7-11 years.
- the land of the free
- the last minute
- the last (or final) straw
- the last straw
- the last word
- the laugh is on me (or you, him, etc.)
- the Law
- (the law of) diminishing returns
- the Law of Moses
- the law of the jungle
- the Left
- the length and breadth of
- the lesser evil (or the lesser of two evils)
- the Lido
- the lie (lay) of the land
- the life and soul of the party (the life of the party)
- the light of day
- the light of one's life
- the lights are on, but nobody's (or no one's)home
- the likes of
- the Line
- the line of least resistance
- the line (or path) of least resistance
- the lion's den
- the lion's share