Etymology works in two directions. You can take a word in modern English and work backwards to its roots, as I did last month with gossipmonger. Another way to approach it is to take a word in an ancient language and work forwards to see what sorts of word it has produced in modern English. This process often illuminates connections between words that are otherwise not obvious. It can also be surprising how much language can be created out of relatively few simple elements, just as the whole of English can be constructed out of the 44 phonemes of RP (received pronunciation) or the 26 letters of the alphabet.
Take the Latin verb tenere (to hold), for example. There are a number of different modern forms where the word has retained the spelling ten- and where the link to the original meaning is more or less obvious: tenet (dogma or principle, a belief held), tenacious (holding fast, tough), tenant (one who holds or possesses land, and by extension one who rents a place), tenure (the right to hold a position), amongst others.
Interestingly, the word also has a parallel history in combination, although spelling changes have tended to obscure the connection. In Latin, tenere could combine with a number of different prepositions used as prefixes, including ab- (off, away from), con- (together), de- (aside), inter- (among), ob- (towards), re- (back) and sub- (under). Modern English is rather like the graveyard of this process, where the forms still exist, but have mostly lost any feel that the words are composite forms: abstain, contain, detain, entertain, obtain, retain and sustain. All these underwent various spelling differences until settling on -tain around the time of Shakespeare.
One more modern result of the word tenere is worth a mention. The tenor of a document is the gist or most important points (from the idea that this is what the document holds). This word is relatively rare, but the same word is more commonly used for a type of male voice. This apparently comes from the fact that that voice (between bass and alto) was usually given the melody line, the most important harmonic element, and so carried the substance of the piece of music.
