Heinlein describes Martian words as "guttural" and "jarring". Martian speech is described as sounding "like a bullfrog fighting a cat". Accordingly, "grok" is generally pronounced as a guttural "gr" terminated by a sharp "k" with very little or no vowel sound (a narrow transcription might be ). William Tenn suggests Heinlein in creating the word might have been influenced by Tenn's very similar concept of "griggo", earlier introduced in Tenn's story "Venus and the Seven Sexes" (published in 1949). In his later afterword to the story, Tenn says Heinlein considered such influence "very possible".