STEP- implies "orphan"

STEP'-CHILD, n. [step and child.] A son-in-law or daughter-in-law, [a child deprived of its parent.]
STEP'-DAME, n. A mother by marriage, [the mother of an orphan or one deprived.]
STEP'-DAUGH-TER, n. A daughter by marriage [an orphan daughter.]
STEP'-FA-THER, n. A father-in-law; a father by marriage only; [the father of an orphan.]
STEP'-MOTH-ER, n. A mother by marriage only; a mother-in-law; [the mother of an orphan.]
STEP'-SIS-TER, n. A sister-in-law, or by marriage, [an orphan sister.]