otapati

1. (otapati se; of snow, ice) to melt; to thaw
   Sneg se već otapa na suncu. — The snow is already melting in the sun.
   Na proleće se led na reci otapa. — In spring the ice on the river thaws.
2. (+ acc.) to melt; to thaw
   Sunce polako otapa sneg na krovovima. — The sun is slowly melting the snow on the roofs.
3. (otapati se; of people, relations) to thaw; to warm up
   Odnosi između dve zemlje se polako otapaju. — Relations between the two countries are slowly thawing.

In the sense 'to melt (by itself)' it is used with se: sneg se otapa.