一同
いちどう · ichidou · JLPT N1 · noun
present
一同 = 一 (one) + 同 (together): everyone present, all as one group
一 means one and 同 means together or same, so 一同 is everyone taken as one unit. It is a formal word for all present or all concerned, as in 一同に感謝する (we all thank you).
一 — single horizontal stroke
一 is one of the simplest pictographs in Chinese, depicting a single horizontal line to represent the number one. It has retained essentially the same form since oracle bone script over 3,000 years ago. By extension it also means 'first,' 'whole,' or 'same.'
同 — 冂 enclosure + 一 + 口 mouth
Originally depicted multiple mouths gathered under one cover or enclosure, suggesting people speaking together in agreement. From this image of voices joining, it came to mean 'same,' 'together,' or 'alike.' The shared cover symbolizes unity.