It is an interesting phenomenon that we use the word several frequently, but people have widely different interpretations of what it means. So before you go on, consider for a moment how many you think several is.
If I say I had several friends over last night, how many do you picture? If I did something several years ago, how long has it been? If I picked several apples, how many were there?
If I remember correctly, this debate started for me when my sister Emily mentioned she had several friends over to her house one night. I asked how many she meant, and she said nine, I believe. I said, that’s not several, that’s a lot! This prompted a lively debate. I myself think of several as 3-4; she says 7-10. Another sister agreed with Emily, and my other sister, and her husband, agreed with me.
I went on to ask a few dozen people this question. It’s also fun to stop someone right after they use the word and ask how many they really mean. I have heard answers ranging from ’1 or more’, up to 10-15 or something.
I’ve found dictionary definitions such as “more than one”, and “more than a few but less than many”.
My definition of ‘a few’ is also 3-4. I would admit that I find a subtle difference in that ‘a few’ is emphasizing the smallness of the number, where ‘several’ is emphasizing the largeness of the number. But I still thought Emily had misrepresented the number of guests she had, whereas she would think I was lying if I said the same thing about three people.
It occurred to me that there’s that line in the Constitution about “several States”, which must have referred to 13+. This set me back for a bit, but I found a dictionary indicating another definition of several that means ‘separate’ or ‘independent’ – and even specifically citing that line in the Constitution. See the Merriam-Webster definition, for instance.
Now, sometimes 3-4 is a lot (as in heart attacks) and sometimes it is very few (as in sugar crystals).
Once I found myself writing a status report at work and saying how ‘several’ people had contributed to a project that week. It was really two, but I was trying to make it sound good. So apparently I go beyond my normal definition when it seems advantageous. Just think if Emily was my manager, and thought I exaggerated the truth by 250% – I might not have a job! 
Thinking about this subject led me to realize there’s a whole world of what I’ll term non-specific quantifiers in the English language: some, a few, multiple, many, a lot, quite a few, tons of, loads of, lots of, a number of, etc. And then a few naughty ones of the form a ****-load of.
‘A couple’ surely means two, although my sister Amy spent much of her youth investigating abuses of that term.
Then there are ones with a hint of a number, but still not specific, like dozens, hundreds, thousands, tens of thousands, millions, etc. My opinion on these is that generally hundreds should mean 200-999 or so. Fewer, and it shouldn’t be plural; more and it should be thousands.
Finally, it’s possible to use a specific number to represent a non-specific amount. Maybe this isn’t as common, and I guess I do it to slightly amuse myself, but I’ll say “there were like 237 ants on the driveway” and stuff like that. It’s supposed to be obvious from context that either my older brother is Rain Man, or I couldn’t possibly know the number so it’s just a guess.
Feel free to comment on your own usage of ‘several’ or these other quantifiers. I wrote down the answers from a couple dozen coworkers (and by that I mean 14-18, hypocritically) and I’ll post them if I find them.
I always figured several had to have a reason for being, something more than a handful (about 5) and definitely less than a dozen. Then again maybe a handful is a lot less than “about 5″ when you’re talking about people who’ve only been around for a couple of years.