Definition of spider fly
1 : a sheep ked, bat fly, or similar usually wingless parasitic dipterous insect
2 : an artificial fly tied to imitate a spider or a spiderlike insect
Start your free trial today and get unlimited access to America's largest dictionary, with:
- More than 250,000 words that aren't in our free dictionary
- Expanded definitions, etymologies, and usage notes
- Advanced search features
- Ad free!
Seen and Heard
What made you want to look up spider fly? Please tell us where you read or heard it (including the quote, if possible).