trochilus
From LSJ
trŏchĭlus: i, m., = τρόχιλος>.
I A very small bird, perh. the golden-crested wren, trochil, Plin. 10, 74, 95, § 203; 8, 25, 37, § 90.—
II In architecture, a semicircular hollow running round the base of a column, a casement, scotia, trochil, Vitr. 3, 3 med.>