The word "backslashes" uses 11 letters: aabcehklsss.
backslashes is a valid word in this word list. For a definition, see the external dictionary links below.
Try a search for backslashes in these online resources (some words may not be found):
Wiktionary - OneLook Dictionaries - Merriam-Webster - Google Search
Each search will normally open in a new window.
Words formed by adding one letter before or after backslashes (in bold), or to aabcehklsss in any order:
p - backsplashes
Shorter words found within backslashes