The author is involved in the making of the Linguistic Atlas of Asia and Africa concerning the system of ‘sibling’ terms. In the process, it has been noticed that general terms for ‘sibling’ often reflect the system which might be alive or outdated (obsolete). In this paper, general terms for ‘sibling’ in Japanese dialects and Ryukyuan dialects are examined and made into linguistic maps using ArcGIS Online. The changes shown in the maps are interpreted referring to the variation of systems. A map of a different lexical item ‘the day before yesterday’ which has forms similar to general terms for ‘sibling’ is compared to prove the existence of homonymic collision.