Breath vs. Breathe

The word "breath" is often erroneously written when "breathe" is what is meant.  This is another instance where spellchecker won't catch the mistake, as both are legitimate words.  "Breathe" is the verb, the action.  "Breath" is the noun, the result of breathing.  When you breathe in, you take in a breath.  When you breathe out, you let out your breath.  (When you're doing neither, you're holding your breath!)

Both words are pluralized merely by adding an "s" at the end.  ("She breathes through her mouth."  "He was taking very deep breaths.")

When spoken, "breathe" is pronounced with a long "e" sound, as well as a soft "th" as with the word "the."  Keeping both of these points in mind can help in remembering the extra "e" at the end.  "Breath" is pronounced with a short "e" sound and a hard "th" like "think."

Incorrect: "It was so hot out, she could hardly breath."
Correct: "It was so hot out, she could hardly breathe."  "I took a deep breath before going outside."