Also, for fear that. In order to avoid or prevent, in case of. For example, They closed all the windows for fear of rain. The variant is always used before a clause, as in She wouldn't let her children climb trees for fear that they would fall. The first term dates from the late 1400s, the second from about 1600.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.