holdup

noun

1. a stoppage; delay or hindrance
2. the act of stopping forcibly and robbing
3. Informal the act of overcharging
4. Chem.
   1. the amount of liquid retained or delayed during fractional distillation and certain types of solvent extractions
   2. the free volume between the resin particles in an ion exchange column
5. Physics the amount of fissionable material being processed or in storage for irradiation in a reactor cycle