(dated) Mount Rainier (a mountain in Washington, United States)

(linguistics, uncommon) trigrade conjugation / (informal) 3-step process

triplane

Short for 三下奴., petty underling; small fry

the three states of matter, namely solid, liquid and gas

Mount Kongō (a mountain in Osaka Prefecture, Japan) / Mount Kongō (a mountain in Niigata Prefecture, Japan)

to work out a way to

devising means to, working out a way to

large triple gate to temple

(phonetics) in Sanskrit phonology, a general term for the three places of articulation that consonants are grouped into: dorsal (/k, g, ŋ/), coronal (/t, d, n/), and labial (/p, b, m/)