insulin as·part (?s?pärt?)n. A rapid-acting insulin analog whose amino acid sequence differs from that of human insulin by the substitution of aspartic acid for proline in the B chain, used in the treatment of type 1 and type 2 diabetes.[aspart(ic acid).]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.