Lewis & Short

allŭvĭo (adl-), ōnis, f. [alluo].

  1. I. In gen., a washing upon, an overflowing, an inundation: adluvione paulatim terra consumitur, Vulg. Job, 14, 19: terra aquarum saepe adluvionibus mersa, App. Mund. p. 67, 41.
  2. II. In the jurists, an accession of land gradually washed to the shore by the flowing of water, alluvial land: quod per adluvionem agro nostro flumen adjecit, jure gentium nobis adquiritur, Dig. 41, 1, 7; 19, 1, 13
    Hence, jura adluvionum et circumluvio num, Cic. de Or. 1, 38, 173; cf. Dig. 41, 1, 12.