| OP | a chain of atoms in a molecule whose ends are not joined to form a ring |
|---|---|
| OP | an incomplete electrical circuit in which no current flows |
| OP | freedom of access |
| OP | the policy of granting equal trade opportunities to all countries |
| OP | start firing a weapon |
| OP | an open recess in a wall at the base of a chimney where a fire can be built |
| OP | bone fracture associated with lacerated soft tissue or an open wound |
| OP | any frame in which a bowler fails to make a strike or spare |
| OP | an informal party of people with hospitality for all comers |
| OP | an interval that does not include its endpoints |
| OP | a letter of protest |
| OP | a marriage in which each partner is free to enter into extraneous sexual relationships without guilt or jealousy from the other |