In my lifetime, "solid-state" first referred to "built with transistors rather vaccum tubes", where vacuum tubes are not 'solid' because their insides include a

In my lifetime, "solid-state" first referred to "built with transistors rather vaccum tubes", where vacuum tubes are not 'solid' because their insides include a partial vacuum and transistors are 'solid'. Extending "solid-state" to mass storage devices that have neither a rotational device nor the necessary internal gap (air or partial vacuum) for either rotation or actuators feels natural…to me.