The action of pressing your thumb (the fat yet short finger on the end) against any other finger is called opposition.
pre- opposition
That is the correct spelling of "thumb."
Oppose is the base of the word opposition.
Rules of thumb
In a Parliamentary system, the Official Opposition is the second largest party in Parliament.
thumb
they do according to my sister
Metacarpo phalngeal joint of Thumb alloys opposition.
Opponens Pollicis
opposition
The thumb is the only structure in the body having a saddle joint.
oppositional movement
Opposition.
Opposition is a special action of the hand, whereby the thumb and little finger are brought around to touch the fingertips. This action occurs at the joints between the carpal bones and the metacarpals of the thumb and little finger.
Opposition
actual the only species that have movable thumbs are Primates, most mammals don't such as dolphins, and such. in case you don't know a primate consists of monkeys, and apes(yes we are apes).
Opposition of the treaty Versailles