what does the word locomotive mean

The irrepressible privateer bounced returning together many major successes. Then in 1628, the Dutch despatched another three large privateer fleets to press home the benefit thus hitting the Spanish even harder. The smaller Dutch ships had the power of speed and manoeuvrability on the heavier Spanish galleons, whose routes were familiar to all or any the privateers. After several battles of varying success, almost all of the Dutch fleet headed home. The Spanish captains therefore, assuming these were now relatively safe, also thought we would set sail, their ships' bellies full of Mexican silver.