Wordnet 3.0
ADJECTIVE (1)
1.
moving at very high speed;
- Example: "a breakneck pace"
The Collaborative International Dictionary of English v.0.48:
Breakneck \Break"neck`\, a.
Producing danger of a broken neck; as, breakneck speed.
[1913 Webster]
The Collaborative International Dictionary of English v.0.48:
Breakneck \Break"neck`\, n.
1. A fall that breaks the neck.
[1913 Webster]
2. A steep place endangering the neck.
[1913 Webster]
WordNet (r) 3.0 (2006):
breakneck
adj 1: moving at very high speed; "a breakneck pace"