flare-up

• flareup

flare +‎ up, from the verb phrase.

flare-up (plural flare-ups)

1. A sudden outbreak, outburst or eruption (originally of flame, but now used more generally of any violent activity or emotion).
   • 2000, Jon Zonderman, Ronald Vender, Understanding Crohn Disease and Ulcerative Colitis‎:

     Although Crohn disease and ulcerative colitis are chronic, they are characterized by periods of remission that last for varying amounts of time, interrupted by flare-ups, when symptoms of the disease become more evident.

   • 2009, Peter Osbaldeston, The Palm Springs Diner's Bible: A Restaurant Guide for Palm Springs, Cathedral City, Rancho Mirage, Palm Desert, Indian Wells, la Quinta, Bermuda Dunes, Indio, and Desert Hot Springs, Gretna, La.: Pelican Publishing Company, →ISBN, page 250:

     The disadvantage of the underfired grill is the potential for flareups, which can cause a burned spot or carbonization. Not only do these taste bad, but they are also carcinogenic.

2. A sudden intensification in activity.

• rapeful