|1.||a policy of temporary secrecy by police or those in charge of security, in order to protect a person, place, etc, threatened with danger, from further risk|
|2.||a baby's blanket, soft toy, etc, to which a baby or young child becomes very attached, using it as a comforter|
|3.||informal anything used or thought of as providing reassurance|
Something that dispels anxiety, as in I always carry my appointments calendar; it's my security blanket. This colloquial term, dating from about 1960, was at first (and still is) used for the blanket or toy or other object held by a young child to reduce anxiety.