With exact use of words; exactly, precisely. Often in the parenthetic phrase strictly speaking or to speak strictly.

(un-, prefix1 affix 5; cf. unerring, adj.)

in strictness: taken or understood strictly; according to a strict conception, definition, or interpretation. More explicitly in strictness of spee…

Strictly speaking; in the narrow sense (of a term, esp. in the natural sciences). Opposed to sensu lato, adv. Cf. stricto sensu, adv.

= sensu stricto, adv.