tor·nil·lo 
(tôr-nĭlō, -nēō)
(tôr-nĭlō, -nēō)n. pl. tor·nil·los
1. See screwbean mesquite.
2. A seismic signal associated with magma flow within a volcano and consisting of low frequency seismic waves that appear on a seismogram as a line resembling a screw seen from the side.
[Spanish, little lathe, screw, screw bean, diminutive of torno, lathe, from Latin tornus; see TURN.]