Afferent: moving towards something; used in reference to blood, lymph, or nerve impulses. Derived from the Latin afferre, ‘bring towards’.

Afferent arterioles in the kidney convey blood towards the glomerular capillaries. Afferent neurons carry impulses towards the central nervous system (and thus are always sensory in nature). Afferent lymphatic vessels carry lymph into lymph nodes.

Afferent arterioles ('a') carrying blood to glomerular capillaries; arrow indicates direction of flow. (Adpated from bicmra.usuhs.mil/)

The opposite of afferent is efferent (from the Latin efferre, to carry off) which refers to movement away from a reference point. Efferent arterioles carry blood out of the glomerular capillaries. Efferent neurons carry impulses from the central nervous system (and thus are motor). Efferent lymphatic vessels carry lymph out of lymph nodes.

An easy mnemonic: Afferent Arrives, Efferent Exits.