Lewis & Short

fluctĭo, ōnis, f. [fluo; cf. fluctus], a flowing, flow (freq. in Plin.): fluctione occulta laborare, Plin. 31, 11, 47, § 127: oculorum, id. 27, 9, 49, § 74; 28, 7, 21, § 73: mulierum, id. 21, 19, 73, § 123: ventris, id. 23, 5, 53, § 99: fluctiones quas Graeci rheumatismos vocant, id. 22, 18, 21, § 46; 22, 25, 68, § 138.