The sourceless light of the cavern and the tunnel seemed to pulse from that weird mechanism.
This mighty cathedral hewn from inside the rock of earth was lit by a soft, white, sourceless light like that in the main tunnel.
The walls of the tunnel now were damp and glistening in the sourceless soft light, tiny trickles running down them.
mid-14c., "support, base," from Old French sourse "a rising, beginning, fountainhead of a river or stream" (12c.), fem. noun taken from past participle of sourdre "to rise, spring up," from Latin surgere "to rise" (see surge (n.)). Meaning "a first cause" is from late 14c., as is that of "fountain-head of a river." Meaning "written work (later also a person) supplying information or evidence" is from 1788.
"obtain from a specified source," 1972, from source (n.). Related: Sourced; sourcing.