(으)로

RuleNoun + (eu)ro: marks means, method, or direction. After most consonants use euro; after a vowel or a final r/l (rieul) use ro.

Curiosity

son-euro sseoyo ("write by hand") and beoseu-ro gayo ("go by bus"). Both are "by," yet one is euro and the other ro. What is the rule?

Intuition

When there is a consonant, a connecting eu slips in to make euro; with no consonant, just ro. The exception: a final r/l already glides smoothly into ro, so it takes ro without eu.

Visualization

See which form attaches to a consonant-final noun (son) versus a vowel-final one (beoseu): son → son-euro, beoseu → beoseu-ro. (The r/l-final jihacheol is the exception: jihacheol-ro.)

Rolemeans / direction

ends in a consonant (except r/l)손hand

ends in a vowel (or r/l)버스bus

Essence

(eu)ro covers a wide range: means (son-euro), tool (yeonpil-lo), direction (hakgyo-ro), material (namu-ro), role (seonsaengnim-euro). The key point is that r/l is the one exception in the batchim rule — an r/l-final noun takes ro just like a vowel-final noun.

Examples

손으로 써요.

I write by hand.

버스로 학교에 가요.

I go to school by bus.

지하철로 갈아타요.

I transfer to the subway.

Mini-quiz

"son__ sseoyo." (I write by hand) — which fits the blank?