at_a_loss
1. [ adjective ] filled with bewilderment
Synonyms: puzzled nonplussed nonplused
Examples:

"at a loss to understand those remarks" "puzzled that she left without saying goodbye"

Related terms: perplexed
2. [ adverb ] below cost
Examples:

"sold the car at a loss"

Similar spelling:   at_all_costs
  at_last
  at_least
  atlas_moth
  at_leisure