Merriam-Webster's Collegiate® Dictionary, 11th Edition
TINKER
I. noun
Etymology: Middle English tinkere
Date: 14th century
1. a usually itinerant mender of household utensils, an unskillful mender ; bungler, gypsy ,
II. verb (tinkered; tinkering)
Date: 1592
intransitive verb to work in the manner of a tinker, transitive verb to repair, adjust, or experiment with, tinkerer noun