weaken
v.v. to make something less strong or to become less strong yourself. You can use it for physical things, like a bridge, or for things you can't touch, like an argument.
v. to reduce the strength, power, or resolve of something; to become less strong or effective. Functions as both a transitive and intransitive verb.
The constant rain will weaken the old stone walls.
The long hours of questioning began to weaken his resolve to keep the secret from his family.
Economists warn that persistent inflation may weaken the national currency, potentially leading to a decrease in purchasing power for the average citizen over the next decade.
From weak + -en.
Transitive when used with an object ('weaken the wall') and intransitive when describing a state ('his pulse began to weaken').
The medicine made him to weakenThe medicine made him weakenAfter the verb 'make' in the active voice, use the bare infinitive without 'to'.