tr. & intr.v. thick·ened, thick·en·ing, thick·ens
1. To make or become thick or thicker: Thicken the sauce with cornstarch. The crowd thickened near the doorway.
2. To make or become more intense, intricate, or complex: The leader's departure thickens the problems. Our apprehension thickened.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.