Merriam-Webster Collegiate Dictionary - strum

 I. noun  Etymology: imitative  Date: 1764 an act, instance, or sound of ~ming  II. verb  (~med; ~ming)  Date: 1777  transitive verb  1.  a. to brush the fingers over the strings of (a musical in~ent) in playing ~ a guitar; also thrum III,1  b. to play (music) on a stringed in~ent ~ a tune  2. to cause to sound vibrantly winds ~med the rigging — H. A. Chippendale  intransitive verb  1. to ~ a stringed in~ent  2. to sound vibrantly  • ~mer noun