All 4 Uses

laboratory
in
I Survived The Eruption of Mount St. Helens, 1980
(Auto-generated)

He works at a lab in Seattle.†
p. 32.9

lab = a workplace where people do scientific or medical research, or produce drugs or chemicals (also used figuratively) OR (as an adjective) related to such a place
With his overgrown curls and faded jeans, Dr. Morales looked more like a singer in a rock band than a person who worked in a laboratory.†
p. 33.1 *
He'd been working on the mountain all day, and was heading back to his lab in Seattle.†
p. 50.1
He'd been safe at his lab here in Seattle when St. Helens erupted.†
p. 88.5

Definitions:

(1) (laboratory)
a workplace where people do scientific or medical research, or produce drugs or chemicals

or (as an adjective): related to such a place
(2) (meaning too rare to warrant focus)
Much more rarely, lab can be used as an abbreviated way of saying Labrador retriever. It is also a rare last name and may indicate someone's initials.