1. A network of relatively inexpensive computers (including PCs), potentially using different processors and hardware architectures, united by Linux and special system-level software into a massively parallel computing system. The end result is a system capable of supercomputer computation at a much lower price. This sort of system is ideal for compute-intensive tasks such as weather modeling, because the calculations can be divided among dozens, hundreds, or even thousands of separate processors all running simultaneously. Sometimes referred to a "Beowulf-class supercomputer", or a super-cluster or hyper-cluster. For more on Beowulf technology, read the following articles: www.linuxworld.com/linuxworld/lw-2000-04/lw-04-parallel.html, and www.ibm.com/press/prnews.nsf/Searchvw/3f4e88b102477aa5852568460067a52a. From I-gloss

2. Famed was this Beowulf: far flew the boast of him, son of Scyld, in the Scandian lands. So becomes it a youth to quit him well with his father's friends, by fee and gift, that to aid him, aged, in after days, come warriors willing, should war draw nigh, liegemen loyal: by lauded deeds shall an earl have honor in every clan. Beowulf is the earliest surviving epic poem written in English. It is a story about a hero of great strength and courage who defeted a monster called Grendel. See History to find out more about the Beowulf hero. There are probably as many Beowulf definitions as there are people who build or use Beowulf Supercomputer facilities. Some claim that one can call their system Beowulf only if it is built in the same way as the NASA's original machine. Others go to the other extreme and call Beowulf any system of workstations running parallel code. My definition of Beowulf fits somewhere between the two views described above, and is based on many postings to the Beowulf mailing list: Beowulf is a multi computer architecture which can be used for parallel computations. It is a system which usually consists of one server node, and one or more client nodes connected together via Ethernet or some other network. It is a system built using commodity hardware components, like any PC capable of running Linux, standard Ethernet adapters, and switches. It does not contain any custom hardware components and is trivially reproducible. Beowulf also uses commodity software like the Linux operating system, Parallel Virtual Machine (PVM) and Message Passing Interface (MPI). The server node controls the whole cluster and serves files to the client nodes. It is also the cluster's console and gateway to the outside world. Large Beowulf machines might have more than one server node, and possibly other nodes dedicated to particular tasks, for example consoles or monitoring stations. In most cases client nodes in a Beowulf system are dumb, the dumber the better. Nodes are configured and controlled by the server node, and do only what they are told to do. In a disk-less client configuration, client nodes don't even know their IP address or name until the server tells them what it is. One of the main differences between Beowulf and a Cluster of Workstations (COW) is the fact that Beowulf behaves more like a single machine rather than many workstations. In most cases client nodes do not have keyboards or monitors, and are accessed only via remote login or possibly serial terminal. Beowulf nodes can be thought of as a CPU + memory package which can be plugged in to the cluster, just like a CPU or memory module can be plugged into a motherboard. Beowulf is not a special software package, new network topology or the latest kernel hack. Beowulf is a technology of clustering Linux computers to form a parallel, virtual supercomputer. Although there are many software packages such as kernel modifications, PVM and MPI libraries, and configuration tools which make the Beowulf architecture faster, easier to configure, and much more usable, one can build a Beowulf class machine using standard Linux distribution without any additional software. If you have two networked Linux computers which share at least the /home file system via NFS, and trust each other to execute remote shells (rsh), then it could be argued that you have a simple, two node Beowulf machine. From Beowulf-HOWTO

3. a multi computer architecture which can be used for parallel computations. It is a system which usually consists of one server node, and one or more client nodes connected together via Ethernet or some other network. It is a system built using commodity hardware components, like any PC capable of running Linux, standard Ethernet adapters, and switches. From Linux Guide @FirstLinux