Oxford English Dictionary
The OED is the definitive record of the English language, featuring 600,000 words, 3 million quotations, and over 1,000 years of English.
Phrases And Sayings, With Meanings And Origins Explained
The meanings and origins of thousands of English phrases, sayings, idioms, expressions and proverbs that we use daily.
Online Etymology Dictionary
Green’s Dictionary of Slang
The free online Dictionary of Affixes
The American Heritage Dictionary entry: teks
Merriam-Webster M-W
World Wide Words