The word "neoteny" is borrowed from the German "Neotenie", the latter constructed by Kollmann from the Greek νέος ("neos", "young") and τείνειν ("teínein", "to stretch, to extend"). The adjective is either "neotenic" or "neotenous". For the opposite of "neotenic", different authorities use either "gerontomorphic" or "peramorphic". Bogin points out that Kollmann had intended the meaning to be "retaining youth", but had evidently confused the Greek "teínein" with the Latin "tenere", which had the meaning he wanted, "to retain", so that the new word would mean "the retaining of youth (into adulthood)".