Sentence:  The boy became volubly friendly and bubbling over with unexpected humour and high spirits. He tried to persuade Cicely to stay away from the ball-room for a fourth dance. Nobody would miss them, he <WSD>explained</WSD>. 
Meaning of the word marked with <WSD> tags:  To make plain, manifest, or intelligible; to clear of obscurity; to illustrate the meaning of.