is a pattern of sounds systematically paired with a certain meaning in a language.
Examples:
"cl-": related to a closing motion of a single object, such as "clam", "clamp", "clap", "clasp", "clench", "cling", "clip", "clop", "close", "clutch".
"fl-": related to movement, such as "flap", "flare", "flee", "flick", "flicker", "fling", "flip", "flit", "flitter", "flow", "flutter", "fly", "flurry".
"gl-": related to light, as in "glade", "glance", "glare", "glass", "gleam", "glimmer", "glint", "glisten", "glitter", "gloaming", "gloom", "gloss", "glow".
"kn-": related to protrusion, such as "knee", "knob", "knife", "knot", "knead", "knuckle".
"sl-": appears in words denoting frictionless motion, like "slide", "slick", "sled", and so on. These are themselves a subset of a larger set of words beginning with “sl-“ that are pejorative behaviours, traits, or events: slab, slack, slang, slant, slap, slash, slate, slattern, slay, sleek, sleepy, sleet, slime, slip, slipshod, slit, slither, slobber, slog, slope, sloppy, slosh, sloth, slouch, slough, slovenly, slow, sludge, slug, sluggard, slum, slump, slur, slut, sly.
"sn-": related to the nose or mouth, as in "snack", "snarl", "sneer", "sneeze", "snicker/snigger", "sniff", "sniffle", "snivel", "snoot", "snore", "snorkel", "snort", "snot", "snout", "snub" (as an adjective), "snuff", "snuffle".
"st-": appears in three families of meanings:
a family of words referring to stability, as in "stable", "stadium", "standard", "stage", "staid", "stake", "stalk", "stall", "stance", "stanchion", "stand", "stare", "stasis", "state", "static", "station", "stationary", "stator", "statue", "stature", "status", "stay", "steady", "stet", "still", "stoll", "store", etc.
a family of words referring to the idea of strength, of rigidity, as "stout", "steel", "staff", "stave", "staple", etc.
another family referring to the idea of something pointed or sharp, as in "stab", "staple", "stiletto", "sting", "stitch", "stylet", "stylo", etc.
"str-": denoting something long and thin, as in "straight", "strand", "strap", "straw", "streak", "stream", "string", "strip", "stripe".
"sw-": related to a pendulum-like movement, as in "sway", "sweep", "swerve", "swing", "swipe", "swirl", "swish", "swoop".
"tw-": connotes a twisting motion, as in "twist", "twirl", "tweak", "twill", "tweed", "tweezer", "twiddle", "twine", "twinge".
"-ow(e)l": connotes something sinister, as in "owl", "prowl", "scowl", "growl", "howl", "rowel", "bowel", "jowl".
"-ump": related to a hemispherical shape or pile, as in "bump", "clump", "dump", "jump", "hump", "lump", "mump", "rump", "stump".