Kyūjitai form of 火薬

to use / to employ / to make use of, to apply / to spend

the past / ancient times

(not of a person) old, aged, antiquated

old

fire / a flame / cooking fire / a firestarter / sparks / light (matches or lighter)

age, era, period (of time) / the times, spirit of the age / antiquity / a time in one's life, one's days (in college etc.)

Kyūjitai form of 薬: a medicine, a drug.

use one thing for many purposes / work someone hard

to use one's head