Dictionary definition of "stimulate"
To rouse to activity or heightened action, as by spurring or goading; excite, provoke
2. To increase temporarily the activity of (a body organ or part).
3. To excite or invigorate (a person, for example) with a stimulant/drug.
There is no such word as "estimulate" Perhaps you mean "estimate? ". If so, that word means to guess,