Chalk this one up as speculation, but it seems like more than coincidence. It is well-known that the surrealistic art of Giorgio de Chirico was an influence on Fumito Ueda when he made Ico, but did he go so far as to name the game after him? As NeoGAF forum member Dunan points out, the last three letters of de Chirico’s name seem to be the inspiration for Ico’s title. 

de Chirico

Source: NeoGAF.