An indicator commonly used in acid/base titrations which turns colourless in acidic solutions and is otherwise (in the concentrations commonly used in labs at least) pale pink. And I mean very pale, so it is f*cking useless without a colour chart and very good eyes. It also turns colourless in solutions of pH greater than 12.
The Kastle-Meyer test shows the presence of blood; a dry swab or piece of filter paper is used to collect a sample, then a few drops of phenolphthalein dissolved in alcohol (due to its insolubility in water) is added, followed by a few drops of hydrogen peroxide - this mixture will turn pink in the presence of blood. If you've ever watched 5 seconds of CSI, you have seen someone doing this.
In the past phenolphthalein has been used as a laxative, but is no longer used due to fears that it is carcinogenic.
Person A - "I'm using phenolphthalein but I can't tell if the solution's acidic yet..."
Person B - "Just make up some results - it'll be more accurate."
The original language, that is to say the language spoken by the people of its country of origin. As opposed to American English (aka 'Anglo-American') and worst of all Microsoft English (though there are a few others which vary from the original to a lesser extent).
The most notable change in the American variant of English is that it has hundreds of changes to spelling, mostly to make it more phonetic, though there are a few words which have been added or their definition changed.
Microsoft English is the language that Microsoft Word describes as 'English (UK)', and remains a mystery to us mortals. No-one knows what the f*ck it is, but it's certainly not quite the same as anything else. I really want some of whatever the programmers were smoking when they made Microsoft Word's spelling/grammar checker (emphasis on the grammar check).
Person A - "WTF?! Look at this grammar 'correction'!"
Person B - "Whoa! What's that all about? I wish MS would just use English English!"