Early Quenya
maira
adjective. excessive, strong
ausi-
prefix. well
mande
adverb. well
tampo
noun. well
vande
adverb. well
There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
A noun in the Qenya Lexicon of the 1910s given as ᴱQ. tampo “a well”, derived from the root ᴱ√TṂPṂ “build”; Tolkien considered transferring the word to ᴱ√TAPA “✱stretch” (QL/93). This word also appeared in the Poetic and Mythological Words of Eldarissa (PME/93).
Neo-Quenya: I think ᴺQ. tampo “well” might be salvaged in Neo-Quenya as a derivative of √TAM “construct”; it is used this way in Helge Fauskanger’s NQNT (NQNT).