v.
 (past and past part. cost)
  - require the payment of (a specified sum) in order to be bought or obtained. 
▸cause or require the expenditure or loss of.
 ▸
informal be expensive for:
 it'll cost you.
 (past and past part. costed)
 estimate the price or cost of.
n.
 the amount that something costs. 
▸the effort or loss necessary to achieve something.
 ▸
(costs)
 legal expenses, especially those allowed in favour of the winning party or against the losing party in a suit.
 
  Phrase
  
    - at all costs 
(or at any cost)
 regardless of the price or the effort needed.  - at cost
 at cost price.  - cost someone dear 
(or dearly)
 involve someone in a serious loss or a heavy penalty.  - to someone's cost
 with loss or disadvantage to someone. 
   
  Etymology
  ME: from OFr. coust (n.), couster (v.), based on L. constare ‘stand firm, stand at a price’.