Other forms: thumbs
Your thumb is the short thick finger that makes the good job sign. It sits apart from the other four and can reach across to touch them all.
That opposition is what makes human hands able to grip, and it is one of the things that separates us from most animals. English uses the word heavily: thumbs up, thumbs down, under somebody's thumb, and a rule of thumb, meaning a rough practical guide. Being all thumbs means being clumsy. As a verb it means to hitch a lift, or to flick through pages, and a well-used book becomes thumbed.
1nounthumbThe short thick digit set apart from the fingers.
“He caught his thumb in the door.”
The thumb is the grown one. Old English þūma goes back to a root meaning to grow, so it is named as the swollen digit, the fat one among the five.
Proto-Indo-European
*tewh₂-
Proto-Indo-European
*tūm- — to grow
Proto-Germanic
*þūmô — thumb
Proto-West Germanic
*þūmō — thumb
Old English
þūma — thumb
Middle English
thombe
English, today
thumb
Built from
Derived from Middle English thombe, thoume, thoumbe (“thumb”), from Old English þūma (“thumb”), from Proto-West Germanic þūmō (“thumb”), from Proto-Germanic þūmô (“thumb”), from Proto-Indo-European tūm- (“to grow”). Cognate with West Frisian tomme (“thumb”), Dutch duim (“thumb”), Low German Duum (“thumb”), German Daumen (“thumb”), Danish, Norwegian Bokmål and Norwegian Nynorsk tomme (“inch”), nrn tum (“thumb”), Swedish tumme (“thumb”), tum (“inch”), Russian дюйм (“inch”), Ancient Greek τύμβος (“burial mound”). Also compare Welsh tyfu (“to grow”), Latin tumēre (“to swell”), Lithuanian tumėti (“to thicken, clot”), ae 𐬀𐬨𐬏𐬙 (“strong”), Sanskrit तुम्र (“strong, thick”). The parasitic ‐b has existed since the late 13th century. Doublet of tomb.
Etymology from Wiktionary, CC BY-SA