Christadelphian, Christadelphia and Christadelphos
A 'Delphos' may be a son, like Delphos or Delphus from Greek mythology was the person from whom the town of Delphi was believed to have derived its name. Or it might also be a daughter like the one of Hyamus and granddaughter of Lycorus. But it might also be a brother or community and in this instance the word is used to denote a community of brothers and sisters in Christ.
The 'Diadelphous' or 'Diadelphian' Di`a*del"phi*an, Diadelphous Di`a*del"phous, a. [Cf. F. diadelphe.] (Bot.)means someone 'of' or 'pertaining to' the class which has itself as two bodies, the one of Christ Jesus in our case and we ordinary people, bundled as one unit, the body of Christ.
A delphos or delphia is also a city and as such several places (cities and counties) in the United States of America may found with such a name. In the old times it also was used to denominate a community of brothers or brethren, or to give such a name to their meeting place. As such we can find for example also a Roman Catholic Church with the name Delphos in the Allan County.
The name Delphia is a Greek baby name. In Greek the meaning of the name Delphia is: "From Delphi", but also to denote "city" or "settling place".
Most important for you and me is to know that Philadelphoa comes from the Greek words 'phila' and 'delphia'. Phila meaning love and delphia meaning brother. Together it means "the country of brotherly love" and with the addition of "Christ" "of Christ" it means that those calling them Christadelphians or being part of Christadelphia are "People who want to unite as brothers and sisters in Christ in a community or in the City of Christ with brotherly love.