Y Zz A Z Zenith Zenith Angle Zero Zero Balance Account (ZBA) Zero Energy Building (ZEB) Zero Sum Game Zero-coupon Bond Zeroth Law of Thermodynamics Zeta Potential Zika Virus Zinc (Zn) Zip Code Zip or Zipper Zirconium (Zr) Zirconium (Zr) Alloy Zodiac (Chinese Astrology) Zoeppritz Equation Zone Zone of Security Zoning ZPG (Zero Population Growth) Zwitterion (or Dipolar Ion) Y Definition Directory A