The Latin word calculus
Word calculus
Meaning pebble, stone
Synonyms saxum, lapis, petra

Other words that might be of interest
fossa ‘ditch’, nemus ‘grove, glade’, limus ‘slime, mud, mire’, arbor ‘tree’, silva ‘forest’, harena ‘sand’, pulvis ‘dust’, humus ‘earth’, terra ‘earth’, ager ‘earth’, mons ‘mountain’, cavus ‘hole, pit’