WordWeb Online

1. Inconclusive as to outcome; close or just even in a race or comparison or competition
   "as they approached the finish line they were neck and neck";
   - head-to-head, nip and tuck [informal]

1. Even or close in a race or competition or comparison
   "the horses ran neck and neck";
   - head-to-head, nip and tuck [N. Amer, informal]

See also: inconclusive

Encyclopedia: Neck and neck