Middle Primitive Elvish
ben
root. corner (from inside), angle from inside
(n)di
root. in
al
prefix. without
dēr
noun. man
imi
root. in
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 (Noldorin only?) root in The Etymologies of the 1930s glossed “corner (from inside), angle from inside” with only one derivative, N. bennas “angle” (Ety/BEN). It might be a latter iteration of ᴱ√VENE “shape, cut out, scoop” from the Qenya Lexicon of the 1910s (originally glossed “small boat”) with derivatives like ᴱQ. vene/G. bent “small boat” and ᴱQ. venie/G. benn “shape, cut” (QL/100-101; GL/22).