dou·ble·tree 
(dŭbəl-trē′)
(dŭbəl-trē′)n.
A crossbar on a wagon or carriage to which two whiffletrees are attached for harnessing two animals abreast.
- overpoweringly
- overpraise
- overprescribe
- overprescription
- overpressure
- overpressurization
- overprice
- overprint
- overprivileged
- overprize
- overproduce
- overproducer
- overproduction
- overproof
- overproportion
- overproportionate
- overproportionately
- overprotect
- overprotection
- overprotective
- overprotectiveness
- overqualified
- overran
- overrate
- overreach