over- + master
overmaster (third-person singular simple present overmasters, present participle overmastering, simple past and past participle overmastered)
- to overpower or overwhelm
- 1897, Bram Stoker, Dracula Chapter 21
- Did I forget! Shall I ever . . . can I ever! Can any of us ever forget that terrible scene! Mina struggled hard to keep her brave countenance, but the pain overmastered her and she put her hands before her face, and shuddered whilst she moaned.