Tutoring English, new words are always interesting – especially ones with everyday meanings. runnel: a brook. Source: Mish, Frederick C. (editor). Merriam-Webster Dictionary. Springfield: Merriam-Webster, 2004.

Self-tutoring about regular expressions with JavaScript: the tutor mentions the idea of the boundary condition. In JavaScript regex, a boundary condition can mean a whitespace or punctuation before or after a word. That’s my understanding, anyway. Source: developer.mozilla.org