least (comparative less)
- superlative form of little: most little;The smallest amount of [something uncountable].
- He earns the least money in his family.
- Of all the sisters, she has the least patience.
- I can only afford to pay the least of the bills.
- 1857, Edmund March Blunt, The American Coast Pilot: Containing Directions for the Principal Harbors, E. & G.W. Blunt, page 135:
- The least water we could find there was 4 fathoms, which bears from the point S.E., and is distant 1½ mile.
- 2004, Jim Baggott, Beyond Measure: Modern Physics, Philosophy, and the Meaning of Quantum Theory, Oxford University Press, page 48:
- Light does not need to know in advance which is the path of least time because it takes all paths from its source to its destination.
Usage notes 
Some grammarians recommend to use least only with uncountable nouns, as in the examples above with the smallest amount of sense:
- 1965, H. W. Fowler, Fowler’s Modern English Usage: Second Edition:
- [W]hen the context—unemotional statement of everyday facts—is taken into account, at a less price ought to be at a lower price, and a lesser prize ought to be a smaller prize.
To such grammarians least is the superlative of a little, not that of little, so it does not mean smallest, but the smallest amount of. With plural nouns, they recommend fewest.
least (negative superlative)
- Used for forming superlatives of adjectives, especially those that do not form the superlative by adding -est.
- It was the least surprising thing.
- In the smallest or lowest degree; in a degree below all others.
- to reward those who least deserve it