by Elio — A much used term nowa­days, "con­ta­gi­on" or in ad­jec­tive form, "con­ta­gi­ous," is de­rived from La­tin 'con­tā­giō' (touch­ing, con­tact, con­ta­gi­on) re­la­ted to 'con­tin­gō' (touch clo­se­ly). In its ori­gi­nal mean­ing, the term re­fer­red so­le­ly to a dis­ease trans­mis­sible by di­rect phy­si­cal con­tact. Now­adays, its mean­ing has been broad­ened to in­clude all com­mu­ni­cable or in­fect­ious dis­ea­ses. As the Wi­ki­pe­dia says: "Of­ten the word...