foster: [OE] The etymological notion underlying foster is of ‘giving food’. Indeed, the Old English verb fōstrian meant ‘feed, nourish’, and it was not until the 13th century that secondary metaphorical senses, such as ‘rear a child’ and ‘encourage, cultivate’, began to emerge. It was a derivative of the Old English noun fōstor ‘food’, which in turn was formed from the same Germanic source, *fōth-, as produced English food. => food
