sole (n.1)

"bottom of the foot" ("technically, the planta, corresponding to the palm of the hand," Century Dictionary), early 14c., from Old French sole, from Vulgar Latin *sola, from Latin solea "sandal, bottom of a shoe; a flatfish," from solum "bottom, ground, foundation, lowest point of a thing" (hence "sole of the foot"), a word of uncertain origin. In English, the meaning "bottom of a shoe or boot" is from late 14c.

sole (adj.)

"single, alone, having no husband or wife; one and only, singular, unique," late 14c., from Old French soul "only, alone, just," from Latin solus "alone, only, single, sole; forsaken; extraordinary," of unknown origin, perhaps related to se "oneself," from PIE reflexive root *swo- (see so).

sole (n.2)

common European flatfish, mid-13c., from Old French sole, from Latin solea "a kind of flatfish," originally "sandal" (see sole (n.1)); so called from resemblance of the fish to a flat shoe.

sole (v.)

"furnish (a shoe) with a sole," 1560s, from sole (n.1). Related: Soled; soling.

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Definitions of sole from WordNet
sole (n.)
the underside of footwear or a golf club;
sole (n.)
lean flesh of any of several flatfish;
Synonyms: fillet of sole
sole (n.)
the underside of the foot;
sole (n.)
right-eyed flatfish; many are valued as food; most common in warm seas especially European;
sole (adj.)
being the only one; single and isolated from others;
the sole heir
the sole example
Synonyms: lone / lonesome / only / solitary
sole (adj.)
not divided or shared with others;
sole rights of publication
Synonyms: exclusive
sole (v.)
put a new sole on;
sole the shoes
Synonyms: resole