Sentence:  And it was while all were passionately intent upon the pleasing and snake-like progress of their uncle that a young girl in furs, ascending the stairs two at a time, <WSD>peeped</WSD> perfunctorily into the nursery as she passed the hallway&mdash;and halted amazed. 
Meaning of the word marked with <WSD> tags:  To look, especially through a narrow opening, or while trying not to be seen or noticed.