be as stubborn as a mule

acoustic(al) current-meter branchial arch (or gill arch) bronchus (dexter et sinister) Diesel-engine generator start test dry assay(ing) entrance pupil fir-hydrant fire unit analyzer gastrobrosis low-flutter magnet luteotrophin magnetic tape driving system Penny Post political-legal organs put an animal out of its misery sapodilla plums spectrum variable ssstsastses-s thermoelastic theory tommy gun