The Collaborative International Dictionary of English v.0.48:

Is- \Is-\
   See Iso-.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Is \Is\, v. i. [AS. is; akin to G. & Goth. ist, L. est, Gr. ?,
   Skr. asti. [root]9. Cf. Am, Entity, Essence, Absent.]
   The third person singular of the substantive verb be, in the
   indicative mood, present tense; as, he is; he is a man. See
   Be.
   [1913 Webster]

   Note: In some varieties of the Northern dialect of Old
         English, is was used for all persons of the singular.
         [1913 Webster]

               For thy is I come, and eke Alain.  --Chaucer.
         [1913 Webster]

               Aye is thou merry.                 --Chaucer.
         [1913 Webster]

   Note: The idiom of using the present for future events sure
         to happen is a relic of Old English in which the
         present and future had the same form; as, this year
         Christmas is on Friday.
         [1913 Webster]

               To-morrow is the new moon.         --1 Sam. xx.
                                                  5.
         Isabel

The Collaborative International Dictionary of English v.0.48:

Iso- \I"so-\, Is- \Is-\ [Gr. 'i`sos equal.]
   A prefix or combining form, indicating identity, or equality;
   the same numerical value; as in isopod, isomorphous,
   isochromatic. Specif.:
   (a) (Chem.) Applied to certain compounds having the same
       composition but different properties; as in isocyanic.
   (b) (Organic Chem.) Applied to compounds of certain isomeric
       series in whose structure one carbon atom, at least, is
       connected with three other carbon atoms; -- contrasted
       with neo- and normal; as in isoparaffine; isopentane.
       [1913 Webster]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

IS
       International Standard (ISO)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

IS
       International Supplement (ODT)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

IS
       Intermediate System (ATM)