pholcid spider; cellar spider
Refers to spiders of the family Pholcidae, especially the common species Pholcus crypticolens. In everyday Japanese, this is the primary meaning.
A cellar spider has built a web in the corner of the ceiling.
Colloquial use for harvestmen (order Opiliones), which are not spiders. Often confused with the spider sense; context usually clarifies.
See also: ざとうむし
We call it a daddy longlegs, but that's not actually a spider.