It is generally known that there is no one-on-one relationship between L1 and L2 vocabulary, and that L1 vocabulary plays an important role in L2 vocabulary development.

Thus, N. Schmitt and M. McCarthy claim that "If the L1 and L2 are similar, there is a much higher likelihood that the initial mapping of the new L2 word will simply be the relabelling of an L1 word, rather than the addition of a totally new conceptual unit."

I would like to investigate what is meant by "similar". What examples can we find of such words?