结冰
jié bīng · HSK 7
to freeze
🧊 结冰 = 结 (form/congeal) + 冰 (ice) → water forms ice, to freeze
冰 means ice; 结 here means to form or congeal (same 结 as in to tie/knot together). Put them together and you get the moment water binds into ice — to freeze over.
结 — silk radical 糸 + lucky 吉 (phonetic)
结 is a semantic-phonetic compound. The silk radical 糸 on the left signals the meaning, since the original sense was tying threads or cords into knots. The right side 吉 (jí) provides the sound. From the literal 'knot' it extended to figurative senses like 'bind,' 'conclude,' or 'form (a bond).'
冰 — ice radical 冫 + water 水
冰 means 'ice' and combines 冫 (the 'ice' radical, originally a pictograph of ice crystals) with 水 'water'. The radical 冫 is itself a simplified form of an older character for ice, so 冰 is essentially 'frozen water'. The form 氷 is a variant still used in Japanese.