Fractionally

• (adv.) By fractions or separate portions; as, to distill a liquid fractionally, that is, so as to separate different portions.
Found on http://thinkexist.com/dictionary/meaning/fractionally/

Fractionally

Frac'tion·al·ly adverb By fractions or separate portions; as, to distill a liquid fractionally , that is, so as to separate different portions.
Found on http://www.encyclo.co.uk/webster/F/70
No exact match found