Proto-Indo-European root meaning "head."

It forms all or part of: achieve; behead; biceps; cabbage; cabochon; caddie; cadet; cap; cap-a-pie; cape (n.1) "garment;" cape (n.2) "promontory;" capital (adj.); capital (n.3) "head of a column or pillar;" capitate; capitation; capitulate; capitulation; capitulum; capo (n.1) "leader of a Mafia family;" capo (n.2) "pitch-altering device for a stringed instrument;" caprice; capsize; captain; cattle; caudillo; chapter; chef; chief; chieftain; corporal (n.); decapitate; decapitation; forehead; head; hetman; kaput; kerchief; mischief; occipital; precipice; precipitate; precipitation; recapitulate; recapitulation; sinciput; triceps.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit kaput-; Latin caput "head;" Old English heafod, German Haupt, Gothic haubiþ "head."

*perə-, Proto-Indo-European root meaning "to grant, allot" (and reciprocally, "to get in return"); possibly related to *pere- (1) "to produce, procure."

It forms all or part of: apart; apartment; bipartient; bipartisan; bipartite; compartment; depart; department; ex parte; impart; jeopardy; multipartite; parcel; parse; part; partial; participate; participation; particle; particular; particulate; partisan; partition; partitive; partner; party; portion; proportion; quadripartite; repartee; tripartite.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit purtam "reward;" Hittite parshiya- "fraction, part;" Greek peprotai "it has been granted;" Latin partem (nominative pars) "a part, piece," portio "share, portion."

*terə-, Proto-Indo-European root meaning "to rub, turn," with derivatives referring to twisting, also to boring, drilling, piercing; and to the rubbing of cereal grain to remove the husks, and thus to threshing.

It forms all or part of: atresia; attorn; attorney; attrition; contour; contrite; detour; detriment; diatribe; drill (v.) "bore a hole;" lithotripsy; return; septentrion; thrash; thread; thresh; throw; threshold; trauma; trepan; tribadism; tribology; tribulation; trite; triticale; triturate; trout; trypsin; tryptophan; turn.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit turah "wounded, hurt;" Greek teirein "to rub, rub away;" Latin terere "to rub, thresh, grind, wear away," tornus "turning lathe;" Old Church Slavonic tiro "to rub;" Lithuanian trinu, trinti "to rub," Old Irish tarathar "borer," Welsh taraw "to strike."

Proto-Indo-European root meaning "right, opposite left," hence "south" (from the viewpoint of one facing east).

It forms all or part of: ambidexterity; ambidextrous; deasil; destrier; Dexter; dexterity; dexterous; dextro-.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit daksinah "on the right hand, southern, skillful;" Avestan dashina- "on the right hand;" Greek dexios "on the right hand," also "fortunate, clever;" Latin dexter "skillful," also "right (hand);" Old Irish dess "on the right hand, southern;" Welsh deheu; Gaulish Dexsiva, name of a goddess of fortune; Gothic taihswa; Lithuanian dešinas; Old Church Slavonic desnu, Russian desnoj. 

Proto-Indo-European root, the stem of demonstrative pronoun meaning "this."

It forms all or part of: cis-; et cetera; harass; he; hence; her; here; him; his; hither; it.

It is the hypothetical source of/evidence for its existence is provided by:  Greek ekeinos "that person;" Latin cis "on this side," citra (adv.) "on this side;" Old Church Slavonic si, Lithuanian is, Hittite ki "this;" Old English hider, Gothic hidre "hither."

Proto-Indo-European root meaning "to dress," with extended form *wes- (2) "to clothe."

It forms all or part of: divest; exuviae; invest; revetment; transvestite; travesty; vest; vestry; wear.

It is the hypothetical source of/evidence for its existence is provided by: Hittite washshush "garments," washanzi "they dress;" Sanskrit vaste "he puts on," vasanam "garment;" Avestan vah-; Greek esthes "clothing," hennymi "to clothe," eima "garment;" Latin vestire "to clothe;" Welsh gwisgo, Breton gwiska; Old English werian "to clothe, put on, cover up," wæstling "sheet, blanket."

Proto-Indo-European root meaning "in."

It forms all or part of: and; atoll; dysentery; embargo; embarrass; embryo; empire; employ; en- (1) "in; into;" en- (2) "near, at, in, on, within;" enclave; endo-; enema; engine; enoptomancy; enter; enteric; enteritis; entero-; entice; ento-; entrails; envoy; envy; episode; esoteric; imbroglio; immolate; immure; impede; impend; impetus; important; impostor; impresario; impromptu; in; in- (2) "into, in, on, upon;" inchoate; incite; increase; inculcate; incumbent; industry; indigence; inflict; ingenuous; ingest; inly; inmost; inn; innate; inner; innuendo; inoculate; insignia; instant; intaglio; inter-; interim; interior; intern; internal; intestine; intimate (adj.) "closely acquainted, very familiar;" intra-; intricate; intrinsic; intro-; introduce; introduction; introit; introspect; invert; mesentery.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit antara- "interior;" Greek en "in," eis "into," endon "within;" Latin in "in, into," intro "inward," intra "inside, within;" Old Irish in, Welsh yn, Old Church Slavonic on-, Old English in "in, into," inne "within, inside."

Proto-Indo-European root meaning "to strike," an extended sense from root *per- (1) "forward, through."

It forms all or part of: compress; depress; espresso; express; impress (v.1) "have a strong effect on the mind or heart;" imprimatur; imprint; oppress; oppression; pregnant (adj.2) "convincing, weighty, pithy;" press (v.1) "push against;" pressure; print; repress; reprimand; suppress.

*rēd-, Proto-Indo-European root meaning "to scrape, scratch, gnaw."

It forms (possibly) all or part of: abrade; abrasion; corrode; corrosion; erase; erode; erosion; radula; rascal; rase; rash (n.) "eruption of small red spots on skin;" raster; rat; raze; razor; rodent; rostrum; tabula rasa.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit radati "scrapes, gnaws," radanah "tooth;" Latin rodere "to gnaw, eat away," radere "to scrape;" Welsh rhathu "scrape, polish."

*meuə-, Proto-Indo-European root meaning "to push away."

It forms all or part of: commotion; emotion; mob; mobile; moment; momentary; momentous; momentum; motif; motility; motion; motive; moto-; motor; move; movement; mutiny; premotion; promote; remote; remove.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit kama-muta "moved by love" and probably mivati "pushes, moves;" Greek ameusasthai "to surpass," amyno "push away;" Latin movere "move, set in motion;" Lithuanian mauti "push on."