• 友達ともだち — friend
• 発達はったつ — development
• 到達とうたつ — arrival; attainment
• 達成たっせい — accomplishment
• 熟達じゅくたつ — mastery; skill
• 上達じょうたつ — improvement; progress
• 伝達でんたつ — transmission; communication
• 配達はいたつ — delivery

達 combines the movement radical 辶 with 羍 (phonetic). It extends from the idea of “proceeding to a place” to achieving goals and, in modern Japanese, also serves as a plural suffix for people (私達・友達).