Learn English – Does “least two weeks to complete” mean it will be done in 2 weeks or more than 2 weeks

Excellent question! The short (and rather unhelpful) answer is that while technically, "a couple" does in fact mean two, it is not always used that way in practice and if you ask several native speakers you're likely to get different responses.

"A couple", "a few", "several"... Words like this are used with various intent. In the particular case of "a couple of weeks" I'm (personally) likely to interpret that as 2-3 weeks away. In any other case where you use "a couple", it depends on the circumstances. I'll get a general idea of what you mean, but we won't necessarily have the same understanding of the situation.

Bob and Marie make a good couple.

Okay, that one's obvious. When you're talking about two people in a relationship as a "couple", clearly there are two of them.

I'll see you in a couple of weeks.

As I said before, this probably means 2, maybe 3 weeks (in my experience). I think this is probably the situation in which you're least likely to cause confusion, though obviously that's not always the case since someone corrected you!

These pretzels are delicious! Can I have a couple more?

Assuming these are snack-sized pretzels... Chances are I'm not just asking you for exactly two, right? Generally people use this to mean "give me some more of them" with "some" being indeterminate. The most common response would be to reach into the bag, grab whatever pretzels you would naturally get at a time, and give them to the person. Sometimes, just to be 'literal' and make a joke, I know people who will carefully count out two pretzels in this situation and give them to you. You'd give them a look, and then they'd give you more. So even native speakers are aware of this disparity, and can find humor in it.

If that's not enough, consider the following xkcd comic, where the author makes fun of the ambiguity of "a couple" and such words:

The author also adds mouseover text to his comic, which reads: "If things are too quiet, try asking a couple of friends whether "a couple" should always mean "two". As with the question of how many spaces should go after a period, it can turn acrimonious surprisingly fast unless all three of them agree." ;)

So there isn't a simple answer for you, I'm afraid, but the answer is it's all very dependent on who you're talking to and how they interpret the word. If your friend corrected you then he has a different interpretation--but that doesn't mean you were wrong!

It basically means "so far", or "up until now":

This is the best iTunes so far.

I'd like to add that yet in the context of "the best X yet" is usually used when describing:

• something fairly new onto the scene,
• made by someone with an established track record of success,
• with hints that there may be more to come.

When describing something older, particularly in the twilight of a career or a product's life, you'd be more likely to use the word ever, instead of yet.

For example, I probably would not say:

Gimme Shelter is the best Rolling Stones song yet!

because that song was release in 1969. Instead, I would proclaim:

Gimme Shelter is the best Rolling Stones song ever!

Moreover, I'm not too sure I'd say:

When You've Got Trouble is the best Liz Longley song yet!

because Liz is an emerging artist without a large library of music to her credit. Instead, I'd probably be more likely to say:

When You've Got Trouble is my favorite Liz Longley song.

Lastly, I'm pretty sure I wouldn't say:

Heath Ledger as the Joker is his best performance yet.

because Mr. Ledger has passed away, and there won't be any future roles that may top his performance in The Dark Knight. I'd probably say instead:

Heath Ledger as the Joker was his best performance.

But, assuming I'm a fan of The Black Keys, I could see myself saying:

"El Camino" by The Black Keys is their best album yet!

because the album is fairly new, the group has put out a decent number of albums, and there is no sign of an immenent breakup of the band.