ul- or ule- or ulo- [from Greek oulon the gums] The gums (ulocace, ulorrhea).

uln- or ulno- [from Latin ulna forearm] Relating to the ulna (ulnocarpal).

ultra- [Latin ultra beyond, further, more, on the other side] Beyond, in excess, extreme (ultraviolet).

un- [Germanic equivalent of Latin un- and Greek an-] Not, opposite, deprived of (unossified).

unci- [from Latin uncus hook] Hook, hooked (uncinate). Compare: onci-.

undec- (or, rarely: hendec-) [from Latin undecim eleven] Eleven (undecane).

uni- [from Latin unus one] One, single (univalent).

ur- or uro- [from Greek oura tail] Tail, taillike, posterior region (Urodela).

ureter- or uretero- [from Greek oureter ureter] Denotes the ureter(s) (ureteralgia).

urin- or urino- or uro- [from Greek ouron urine] Urine (urinoscopy).

vagin- or vagino- [from Latin vagina sheath, scabbard] Denotes the vagina (vaginitis).

vas- or vaso- [from Latin vas vessel, dish, vase] Blood vessel (vasodepressant).

vascul- or vasculo- [from Latin vasculum small vessel] Blood vessel (vasocularity).

ven- or veni- or veno- [from Latin vena blood vessel, vein] (1) vein (venisection); (2) vena cava (venoatrial).

ventr- or ventri- or ventro- [from Latin venter, ventris stomach, belly, womb] (1) in humans: denotes the belly or front; (2) in animals: denotes the lower surface (ventrolateral).

vermi- [from Latin vermis worm, maggot] Worm (vermiform).

vesicul- or vesicul- [from Latin vesicula small bladder or blister] Denotes vesicle(s) (vesicular).

vibr- or vibri- [from Latin vibrare to shake or vibrate] Denotes vibration; hence, in a bacterium, the presence of flagella is implied (Vibrio).

vill- or villi- [from Latin villus shaggy hair] Denotes a villus or villi (villiform, vilosity).

viri- [from virus] Virus (viricide).

viscer- or viscero- [from Latin viscus internal organ] Pertaining to the interal organs (visceral).

vitre- or vitreo- [from Latin vitreus glassy] Like glass; clear as glass, glassy (vitreous).

viv- or vivi- [from Latin vivus alive, living] Alive, living; lively (vivisection).

vulv- or vulvo- [from Latin vulva womb] Denotes the vulva (vulvar).

xanth- or xantho- [from Greek xanthos yellow] Yellow (xanthous).

xen- or xeno- [from Greek xenos stranger, foreigner] Foreign, strange, intruding (xenograft).

xer- or xero- [from Greek xeros dry] Dry (xeric).

xiphi- or xipho- [from Greek xiphos sword] Denotes the xiphoid process (xiphocostal).

xyl- or xylo- [from Greek xylon wood] Wood (xylem).

yocto- [prefix in International System of Units] 10^-24 (yoctogram).

yotta- [prefix in International System of Units] 10²⁴ (yottaFLOPS).

zepto- [prefix in International System of Units] 10^-21 (zeptomole).

zeta- [prefix in International System of Units] 10²¹ (zetaFLOPS).

zinco- Pertaining to or containing the element zinc.

zirco- Pertaining to or containing the element zirconium.

zo- or zoo- [from Greek zoon animal] (1) of or relating to animals (zoology, zoophagous, zoosterol); (2) capable of movement (zoocytium).

zyg- or zygo- [from Greek zygon yoke, tying element] Union, fusion, yoking (zygote).

zym- or zymo- [from Greek zymosis fermentation] Ferment, enzyme (zymotic).