The Latin termination « -trum » is quite old and has the basic meaning “means of/for” (+ verbal noun).
Examples are as follows:

arātrum, -ī, n.

“means for plowing” (arāre):  plow

claustrum, -ī, n.

“means for locking up or barring” (claudere):  lock, bar, bolt;  barrier;  door, gate;  dam, dike, enclosure;  barricade, bulwark;  mediæval cloister

feretrum, -ī, n.

“means for bearing or carrying” (ferre):  litter, bier

fulgētrum, -ī, n.

“lightning without thunder” (fulgēre):  modern:  “flash” (on a camera)

haustrum, -ī, n.

“means for drawing or scooping (a fluid)” (haurīre):  water pump, scooping wheel

mōnstrum, -ī, n.

“means of warning” (monēre):  ominous sign or manifestation, monstrosity, portent, monster;  ghost

mulctrum, -ī, n.

“means for holding milk” (mulgēre):  milk pail

plaustrum, -ī, n.

“means of thumping along” (plaudere):  wagon, cart

rāstrum, -ī, n.

“means for raking” (rādere):  rake, toothed hoe

rōstrum, -ī, n.

“means for gnawing or biting at” (rōdere):  bill, beak, snout, muzzle

rutrum, -ī, n.

“means for digging or churning up” (ruere):  shovel, spade

spectrum, -ī, n.

“means for discerning” (specere):  mental image, visualization, percept, idea;  spectre

trānstrum, -ī, n.

“means for spanning” (trāns):  cross-timber (from side to side in a vessel), rower’s bank (usu. pl.)

verētrum, -ī, n.

“parts of modesty” (verērī):  sexual organs