Sentence:  I'd always found the royals a cold proposition, Diana excepted, but the sight of that little boy, his head bent, not daring to look up at his mother's <WSD>coffin</WSD> in front of him was, and remains, genuinely heartbreaking. 
Meaning of the word marked with <WSD> tags:  A rectangular closed box in which the body of a dead person is placed for burial.