完全
かんぜん · kanzen · JLPT N3 · na-adj
completeness
完全 = finished (完) + whole (全): all of it, done
完 means to finish or complete, as in 完了 (kanryou, completion). 全 means whole or all, as in 全部 (zenbu, everything). Put together: every part done with nothing missing, which is completeness. Kanzen ni (完全に) means fully or totally.
完 — roof 宀 + yuán 元 (phonetic)
完 is a semantic-phonetic compound: the roof 宀 suggests a house or enclosure, while 元 supplies the sound 'yuán/wán'. Originally it meant a building that was intact or whole, and the sense broadened to 'complete, finish, whole'.
全 — enter 入 on top + jade 玉
Originally written as 入 (enter) over 玉 (jade), depicting a complete, unflawed piece of jade kept in storage. From this image of a perfect jade came the meanings 'whole,' 'complete,' and 'entire.' The top component is sometimes written as 人.