Wordnet 3.0
ADJECTIVE (1)
1. 
 belonging to or existing in times before recorded history; 
- Example: "prehistoric settlements"- Example: "prehistoric peoples"[syn: prehistoric, prehistorical]
WordNet (r) 3.0 (2006):
prehistorical
    adj 1: belonging to or existing in times before recorded
           history; "prehistoric settlements"; "prehistoric peoples"
           [syn: prehistoric, prehistorical]