# ser vs serum

> English confusable word pair

## The two words

### ser
*noun · frequency rank #15,268*
Alternative spelling of sir.

### serum
*noun · IPA /ˈsɪəɹəm/ · frequency rank #10,609*
Ellipsis of blood serum.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/vs/ser-vs-serum