reserve
UK: rɪˈzɜːv | US: rɪˈzɜːrv
n. a supply of something kept for future use
vt. to keep or set aside for a particular purpose
n. restraint or caution in expression or action
The word "reserve" traces back to Latin reservare ("to keep back, save"), combining re- (back) and servare (to keep). It entered Middle English via Old French reserver, retaining the core idea of withholding or preserving for future use. The dual meanings of "storing resources" and "exercising restraint" both stem from this original sense of deliberate retention.
The library has a reserve of rare books for researchers.
She decided to reserve her opinion until more evidence was available.
The hotel requires guests to reserve rooms in advance during peak season.
He spoke with reserve, careful not to reveal too much.
The army keeps a reserve of supplies for emergencies.