A waif (from the Old French guaif, 'stray beast')[1] is a person removed, by hardship, loss or other helpless circumstance, from their original surroundings. The most common usage of the word is to designate a homeless, forsaken or orphaned child, or someone whose appearance is evocative of the same.
As such, the term is similar to a ragamuffin or street urchin, although the main distinction is volitional: a runaway youth might live on the streets, but would not properly be called a waif as the departure from one's home was an exercise of free will. Likewise, a person fleeing their home for purposes of safety (as in response to political oppression or natural disaster), is typically considered not a waif but a refugee.