Origin: French suffix -ier
Collier has 3 different meanings across 2 categories:
someone who works in a coal mine
"The old collier walked out of the shaft covered in soot after his final shift of the year."
A person in the business or occupation of producing (digging or mining) coal or making charcoal or in its transporting or commerce.
"The old collier loaded his wagon with fresh coal before heading down to the valley town."
A surname, from occupations​.
"My neighbor's last name is Collier because his great-grandfather worked as a coal miner."