loom large

Appear imminent in a threatening, magnified form. For example, The possibility of civil war loomed large on the horizon, or Martha wanted to take it easy for a week, but the bar exam loomed large. This term employs loom in the sense of “come into view,” a usage dating from the late 1500s.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.