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All of the dictionaries listed below are based on Wordnet and available for free. They are a good place to start if you want to learn about the semantic relationships that exist between words.
If your not sure how Wordnet differs from a conventional dictionary then do not fear just read on.
Firstly, words are grouped into synonym sets (synsets). Each word contained within a synset can replace any of the others without changing the meaning of what is said.
Secondly, semantic relationships are defined between words (Synsets). For instance if you want to explore words that refer to different ways of walking you can look up all the troponyms of the verb walk. For instance, space walk and march are troponyms of the verb walk.
Troponyms for the verb walk – travel, go, move, locomote:
=> tramp down, trample, tread down
=> lollop
=> tap
=> stumble, falter, bumble
=> spacewalk
=> foot, leg it, hoof, hoof it
=> toe
=> traipse, shlep
=> perambulate, walk about, walk around
=> ambulate
=> sneak, mouse, creep, pussyfoot
=> wade
=> tittup, swagger, ruffle, prance, strut, sashay, cock
=> sleepwalk, somnambulate
=> slink
=> limp, gimp, hobble, hitch
=> shuffle, scuffle, shamble
=> stroll, saunter
=> amble, mosey
=> prowl
=> skulk
=> toddle, coggle, totter, dodder, paddle, waddle
=> promenade
=> march
=> stride
=> hike
=> slog, footslog, plod, trudge, pad, tramp
=> tiptoe, tip, tippytoe
=> stalk
=> flounce
=> stagger, reel, keel, lurch, swag, careen
=> stagger, flounder
=> stomp, stamp, stump
=> lumber, pound
=> pace
=> tread, trample
=> slouch
=> mince
=> clump, clomp
=> march, process
=> step
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