It depends on the context. For instance you get something free in a shop you say it as"elavasam" If it is used to refer to freedom You say "Viduthalai"
you say ''oothaa'' to say purple in tamil
you say ''appa'' in order to say dad in tamil
you say ''kann'' in order to say eye in Tamil
you say ''kaal'' in order to say leg in tamil
you say ''amma'' in order to say mum in tamil
you say ''koodam'' in order to say living room in tamil
We say paal for milk in Tamil.
you say ''mooku'' in order to say nose in tamil
if you want to say 30 in Tamil you say ''mupathu''.
you say ''panirandu'' in order to say twelve in Tamil
you say ''kaathu'' in order to say ear in Tamil
you say ''vaay'' in order to say mouth in tamil