1
general::
Also, seize upon. 1. Grab or take hold of suddenly, as in He seized on the bell rope and started to pull vigorously, or She seized upon every opportunity to present her side of the story. [Late 1600s] 2. Resort to some action, especially out of dire necessity, as in He seized upon any excuse, no matter how farfetched.
American Heritage Idioms
2
general::
Phrase(s): seize (up)on something
1. Lit. to grasp something tightly. (Upon is formal and less commonly used than on.) • Dave seized upon the knob of the door and yanked hard. • I seized on the railing and held on tight. 2. Fig. to accept or adopt something, such as a plan, idea, etc. • I heard her ideas and seized upon them immediately. • The committee seized on my plan at once.
McGrawhill's American Idioms And Phrasal Verbs