[1] : The Collaborative International Dictionary of English v.0.48

least \least\ l=est, a. oe. last, lest, as. l=aesast,
   l=aesest, superl. of l=aessa less. see less, a. used
   as the superlative of little.
   smallest, either in size or degree; shortest; lowest; most
   unimportant; as, the least insect; the least mercy; the least
   space.
   1913 webster

   note: least is often used with the, as if a noun.
         1913 webster

               i am the least of the apostles.    --1 cor. xv.
                                                  9.
         1913 webster

   at least, or at the least, at the least estimate,
      consideration, chance, etc.; being no less than; hence, at
      any rate; at all events; even. see however.
      1913 webster

            he who tempts, though in vain, at least asperses
            the tempted with dishonor.            --milton.
      1913 webster

            upon the mast they saw a young man, at least if he
            were a man, who sat as on horseback.  --sir p.
                                                  sidney.
      

   in least, or in the least, in the least degree, manner,
      etc. "he that is unjust in the least is unjust also in
      much." --luke xvi. 10.

   least squares math., a method of deducing from a number
      of carefully made yet slightly discordant observations of
      a phenomenon the most probable values of the unknown
      quantities.

   note: it takes as its fundamental principle that the most
         probable values are those which make the sum of the
         squares of the residual errors of the observation a
         minimum.
         1913 webster
see also:
less at least at the least however in least in the least 
least squares 

[2] : WordNet (r) 2.0

in the least
     adv 1: to any extent at all; "are you in the least interested?"
            syn: even a little
     2: in the slightest degree or in any respect; "are you at all
        interested? no, not at all"; "was not in the least
        unfriendly" syn: at all, the least bit
see also:
even a little at all the least bit 

Least >> L Words
Least, definition of term: Least
least_pag1.html

Least Significa >> L Words
Least Significa, definition of term: Least Significa
least+significa_pag1.html

At Least >> A Words
At Least, definition of term: At Least
at+least_pag1.html

Least Of All >> L Words
Least Of All, definition of term: Least Of All
least+of+all_pag1.html

In The Least >> I Words
In The Least, definition of term: In The Least
in+the+least_pag1.html