The other day, I noticed the following wrong etymology in a Yoga book (written by a western lady) - that "pranayama = prana + yama = breath + control". Actually, പ്രാണ + യമ = പ്രാണയമ and not പ്രാണായാമ. To get the latter, the word needs to be split as പ്രാണ + ആയാമ, or stretching of breath.
A related word is വ്യായാമം = വി + ആയാമം = cross-stretching. So exercise was orginally cross stretching.
The prefix വി (cross, against) appears in a lot of common mallu words mostly disguised as വ്യ (വി + അ) , as seen in the following:
വ്യതിയാനം, difference or variation, is വി + അതി + യാനം, "to overshoot against (a set mark, probably)"
വ്യഗ്രം, eager, is വി + അഗ്രം, "up against the edge"
വ്യാഖ്യാനം, explanation, is വി + ആഖ്യാനം, "cross explain"
Of course, there is another prefix വി, which is an intensifier which appears in വിജ്ഞാനം, വിശുദ്ധം, etc.