API Application Programming Interface (and other meanings); a library for programmers to more easily achieve certain tasks.
Backlink A link pointing from someone else's web page back to the page in question (e.g. your page). Usually the more (relevant) backlinks a page receives, the higher it ranks in Google for certain search queries.
BackRub The name given to the precursor to Google.
Blog A blog or weblog is an online news journal usually written by a single person or a small group, covering any imaginable subject. New entries are posted on top, often with a way to comment on the entry. The blogosphere or blogspace on the other hand is the "universe" of all blogs. Splogs are "spam blogs" which copy content from elsewhere to make money with ads. Vlogs are video blogs, and podcasts are blog-like audio shows that can be downloaded to the iPod or other MP3 players.
Cookie On the web, a small data file a website saves on your computer through your browser. This file is used to memorize e.g. a log-in status, or to better understand your browsing behavior.
Data center A Google data center is a group of servers delivering specific search results to you.
Deep web The kind of websites that are usually hidden from free search engines (either because they are paid content, or because the search engines do not understand how to crawl these sources).
Egogoogling To search for one's own name in Google. (Also: autogoogling, egosurfing.)
Google Google means either Google Inc., the company, or Google the web search engine, or – as in "to google" – it's a verb meaning "to search."
Google Algos A short-hand for "Google's algorithms," meaning the technical specifics of how Google ranks its result pages (the details of which are only really known to those who work at Google).
Google cache Google makes a copy of every website and allows searchers to view these copies (unless the webmaster prevents this with the "robots.txt" file, or so-called meta-tags).
Googlebomb A link campaign trying to discredit a group, company or person. Repeated links with the same link text are used to connect a negative Google search to a certain web page.
Googlebot This software program crawls (or "spiders") the web for content. The content is indexed and later appears in Google search results.
Googlebowling A rumored black-hat methodology to hurt a competitor's website through a link campaign.
Googledance Noticeable updates to the structure of the Google result rankings. (Some major "Google updates" are even given names, like "Google Florida.")
Googlefight Putting two search queries against each other to see which one returns the highest page count on the Google results page.
Googlejuice The popularity that makes a web page appear high in Google search results. For example, "to give someone Googlejuice" can mean to link to someone (because a link to another page increases its value in the eyes of Google). A site which has "a lot of Googlejuice" is usually a web page with a high PageRank.
Googleplex The Mountain View headquarters of Google Inc.
Googler An employee of Google Inc. (a Noogler on the other hand is a new Google employee, and a Xoogler is an Ex-Google employee).
Googlewhack Finding only a single result using two words from the dictionary.
Googlosophy The science of all things Google.
Googol A 1 followed by 100 zeroes. The Google founders often quote this word as origin of how they came up with the word "Google."
IP Often a shorthand for Internet Protocol address, meaning the uniquely identifiable number your computer has when you're online.
Meme On the web, this refers to an idea that quickly spreads from one site to another, virus-like.
Meta search A search engine which itself uses other search engines to determine its results.
Onebox result For certain searches, Google displays an info-box above the actual organic search results. This box may display more direct information (like the answer to a question), or a link to related services (like Google News).
Operator A syntax command to trigger specific Google search functionality. For example, the site operator (as in "site:searchenginewatch.com/blog") allows you to restrict your search to a single domain.
Page count The Google page count is an approximate number telling the searcher on how many web pages the terms in the query appear. For example, searching for "the" returns over 18 billion pages at this time (Google only allows you to see the first 1,000 results for any single search, though).
PageRank The general "value" of a website in the eyes of Google. In a nut-shell, the value is derived from analysis of how many pages link to a certain page (and also, how many pages link to the pages that link to a certain page!). Usually, the higher the PageRank, the more likely this page appears on top of search results often. This value ranges from 0-10, with 10 being the best (and most rare) of values. New websites will always start out with a "PR" of 0. You can check a page's PageRank by installing the Google Toolbar for your browser.
Phrase search When you put quotes around your Google search query, Google only finds exact (or almost exact) matches.
RSS Really Simple Syndication (and other meanings), a feed format allowing you to subscribe to a blog or other regularly updated online content.
SEO Search Engine Optimization; the art (sometimes: dark art) of bringing websites on top of search engine results. An SEO contest is a competition to bring your own site on top of search engines – usually Google – for a specific search. There are black-hat and white-hat SEO strategies (the black-hat strategies can result in a website being "Googleaxed," also known as the Google Death Penalty, a full ban within the Google search results).
Stop words Traditionally, words like "the" or "a" which search engines ignore (Google doesn't have these stop words anymore).
Weblog See blog