detriment, disadvantage, or deprivation from failure to keep, have, or get

to bear the loss of a robbery.

something that is lost

The painting was the greatest loss from the robbery.

an amount or number lost

The loss of life increased each day.

the state of being deprived of or of being without something that one has had

the loss of old friends.

death, or the fact of being dead

to mourn the loss of a grandparent.

the accidental or inadvertent losing of something dropped, misplaced, stolen, etc.

to discover the loss of a document.

a losing by defeat; failure to win

the loss of a bet.

failure to make good use of something, as time; waste.

failure to preserve or maintain

loss of engine speed at high altitudes.

destruction or ruin

the loss of a ship by fire.

a thing or a number of related things that are lost or destroyed to some extent

Most buildings in the burned district were a total loss.

Military .

the losing of soldiers by death, capture, etc.

Often, losses. the number of soldiers so lost.

Insurance . occurrence of an event, as death or damage of property, for which the insurer makes indemnity under the terms of a policy.

Electricity . a measure of the power lost in a system, as by conversion to heat, expressed as a relation between power input and power output, as the ratio of or difference between the two quantities. ?

at a loss

at less than cost; at a financial loss.

in a state of bewilderment or uncertainty; puzzled; perplexed

We are completely at a loss for an answer to the problem.