plumb

To determine the depth, generally of a liquid; to sound.

To attach to a water supply and drain.

(transitive, figuratively) To think about or explore in depth, to get to the bottom of, especially to plumb the depths of.

To use a plumb bob as a measuring or aligning tool.

To accurately align vertically or horizontally.

(dated) To seal something with lead.

(intransitive) To work as a plumber.

(rare) To fall or sink like a plummet.

(US, colloquial, figuratively, obsolete) To trace a road or track; to follow it to its end.

(nautical) To position vertically above or below.