Sentence:  There still remains in the Islands, though it is passing fast away, the custom of <WSD>fosterage</WSD>. A Laird, a man of wealth and eminence, sends his child, either male or female, to a tacksman, or tenant, to be fostered. 
Meaning of the word marked with <WSD> tags:  The act of fostering another's child as if it were one's own.