Z

1. Astron. zenith distance.

2. zone.

Symbol.

1. the 26th in order or in a series, or, when I is omitted, the 25th.

2. (sometimes l.c.) the medieval Roman numeral for 2000. Cf. Roman numerals.

3. Chem., Physics. atomic number.

4. Elect. impedance.

Z⁰

Symbol, Physics. See Z-zero particle.

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