WordNet (r) 3.0 (2006):

to the letter
    adv 1: in every detail; "the new house suited them to a T" [syn:
           to a T, to the letter, just right, to perfection]

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "to the letter":
   absolutely, dead, definitely, directly, even, exactly, expressly,
   faithfully, in all respects, in every respect, ipsissimis verbis,
   just, literally, literatim, plumb, point-blank, positively,
   precisely, right, rigidly, rigorously, square, squarely, straight,
   strictly, undeviatingly, unerringly, verbally, verbatim,
   verbatim et litteratim, word by word, word for word