dif·fer·en·ti·a·tion 
(dĭf′ə-rĕn′shē-āshən)
(dĭf′ə-rĕn′shē-āshən)n.
1.
a. The act or process of differentiating.
b. The state of becoming differentiated.
2. Mathematics The process of computing a derivative.
3. Biology The process by which cells or tissues undergo a change toward a more specialized form or function, especially during embryonic development.