The great majority of -culum words[186] also are concrete. They may be grouped into three classes as far as their verb stems are concerned: (1) Those denoting instrument; (2) Those denoting place; (3) Those denoting the object of the action expressed by their verb stems.
1. Nouns denoting instrument.
Baculum (etymology very uncertain, but probably same root as seen in βαίνω) from its verb stem, should mean only a walking stick, but it is applied to almost any kind of staff or sceptre: proximus lictor converso baculo oculos misero tundere vehementissime coepit, Verr. 5, 142; baculum aureum regis berylli distinguebant, Curt. 9, 1, 30.
Everriculum (everro) is a sweep net (also used figuratively): neque everriculo in litus educere possent, Varr. R. R. 3, 17, 7; quod umquam huiusmodi everriculum ulla in provincia fuit?, Verr. 4, 5, 3.
Ferculum (fero) is that on which anything is carried: spolia ducis hostium caesi suspensa fabricato ad id apte ferculo gerens in Capitolium ascendit, Liv. 1, 10, 5; ubi multa de magna superessent fercula cena, Hor. S. 2, 6, 104.
Gubernaculum (guberno) is an instrument for guiding: piscium meatus gubernaculi modo regunt caudae, Plin. 11, 50, 111; hic ille naufragus ad gubernaculum accessit, et navi, quod potuit, est opitulatus, Inv. 2, 154.
Incerniculum (incerno) is an instrument for sifting, a sieve; it occurs only twice, and it is difficult to see how it differs from another noun on the same stem, cribrum: opus est incerniculum unum, cribrum unum, Cato, R. R. 13; Athenienses decretum fecere, ne frumentarii negotiatores ab incerniculis eum [mulum] arcerent, Plin. 8, 44, 69. In the latter example the incernicula are the vessels in which bran, sifted from the flour, was set up for sale.
Operculum (operio) like operimentum is an instrument for covering: aspera arteria tegitur quodam quasi operculo quod ob eam causam datum est, ne spiritus impediretur, N. II, 136; operculum in dolium imponito, Cato, R. R. 104.
Perpendiculum (perpendo) is a plumb line, but is found most frequently with ad forming an adverbial phrase meaning perpendicularly: non egeremus perpendiculis, non normis, non regulis, Cic. A. fr. 8; tigna non directa ad perpendiculum, sed prone et fastigate, B. G. 4, 17.
Piaculum is a means of appeasing, an offering; perhaps also the appeasing itself; and the act requiring expiation: decrevit habendas triduum ferias, et porco femina piaculum pati, Leg. 2, 22; nonne in mentem venit quantum piaculi committatur? Liv. 5, 52; duc nigras pecudes: ea prima piacula sunto, Aen. 6, 153.