My son has a pretty eclectic selection of vocabulary. Some words seem to have been picked up from my wife and I repeating them (such as "uh-oh" and "daddy"). Others seem to have been learned without us doing much to single them out ("balloon", "blue", and "duck" for example).
Other words we've been trying to teach him (see here) seem unaffected by repetition.
Some words he's learned seem completely random. For example, when looking at my iPhone booting up, he pointed to the Apple logo, and said "ball". I said "that's not a ball, that's an apple", and he immediately smiled and said "apple" quite clearly. Yet he doesn't seem to associate the word with the logo, or even my phone, as it seems to be a catch-all word to him (it is now his favorite words, but seems to be used for anything from "I'm bored" to "hello!" to "oooo! Look at the wind chime!").
I can't seem to figure out what the pattern (or patterns?) is to how he chooses his words. Is there one?