Which adjective describes actions conducted in a stealthy or clandestine manner?

The adjective 'surreptitious' accurately describes actions that are conducted in a stealthy or clandestine manner. It originates from the Latin word "surreptitius," which means "taken secretly." When something is surreptitious, it often implies that the action is done in a way that is meant to escape notice or to avoid drawing attention. This could refer to secretive behavior, such as sneaking around to avoid being seen or engaging in activities that should be kept hidden.

In contrast, the other options do not carry the same connotation of stealth or secrecy. 'Teetotal' refers to someone who abstains from alcohol, 'somnolent' pertains to drowsiness or sleepiness, and 'striated' describes something that is marked by striations, often in a physiological context concerning muscle fibers or other patterns. Thus, 'surreptitious' stands out as the only term that effectively conveys the essence of hidden or secretive actions.