to prevent injury, decay, waste, or loss of

Conserve your strength for the race.

to use or manage (natural resources) wisely; preserve; save

Conserve the woodlands.

Physics, Chemistry . to hold (a property) constant during an interaction or process

the interaction conserved linear momentum.

to preserve (fruit) by cooking with sugar or syrup.

Often, conserves. a mixture of several fruits cooked to jamlike consistency with sugar and often garnished with nuts and raisins.