Sentence:  When he was bent over behind the wheel of the station wagon , feeling in his trouser cuffs for the <WSD>ignition</WSD> key which he had dropped a moment before , she came out of the house with an enormous Rumanian shawl over her head , which she had bought in that country during one of their trips abroad , and handed him a clean handkerchief through the window . 
Meaning of the word marked with <WSD> tags:  a key that operates the ignition switch of an automotive engine