Definitions beginning with M

A large tissue cell that does not circulate in the blood. They are also important in producing the signs and symptoms of hypersensitivity reaction, such as those of an insect sting, and certain forms of asthma.
DHHS - Cite This Source - This Definition
Browse Related Terms: anemia, bone marrow, Engraftment, erythrocyte, Erythroid cell, hematopoiesis, hematopoietic stem cell, Platelets, Red Blood Cells, Thrombocyte (Platelet)

A growth or lump of mast cells (a type of white blood cell). Mast cell tumors can involve the skin, subcutaneous tissue, and muscle tissue. Also called mastocytoma.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: agranulocyte, cytotoxic T cell, incubated, killer cell, mast cell, mastocytoma, monocyte, Schiller test, tumor infiltrating lymphocyte

Pertaining to microforms, the master is the original film from which duplicates are made. The master usually serves as the security copy of the filmed records and is maintained in a secure and controlled, off-site, records center location.
State of Utah - Cite This Source - This Definition
Browse Related Terms: back up, Backup, duplicate, Replication, security copy, Vital Record

The first sector on a hard disk, which begins the process of starting the computer. The MBR contains the partition table for the disk and a small amount of executable code called the master boot code.
Microsoft - Cite This Source - This Definition
Browse Related Terms: BCD, BIOS boot order, Boot Configuration Data, boot partition, boot sector, MBR, operating system volume, slack space, system volume

A device that generates periodic, accurately spaced signals that are used for such purposes as timing, regulation of the operations of a processor, or generation of interrupts.
ATIS - Cite This Source - This Definition
Browse Related Terms: clock, Coordinated Universal Time (UTC), International Atomic Time (TAI), primary reference source, Rate Center, UTC(i)

the unique mandatory file containing access conditions and optionally DFs (dedicated files) and/or EFs (extended frames). [T1.707-1998]
ATIS - Cite This Source - This Definition
Browse Related Terms: FAQ file, File, file-oriented applications, frequently asked questions, push-down file, Root (SD card), .sbf, spike file, superuser, .tgz

A unique system file that essentially acts as a database, containing information on all the files and subdirectories located within the NTFS logical volume (partition). There is at least one record for every file and subdirectory on the NTFS logical volume and each one is 1024 bytes in length and contains information, known as attributes, that tell the system how to deal with the file or directory associated with the record. If the full 1024 bytes are not used, the record can contain information from previ
AmDoc - Cite This Source - This Definition
Browse Related Terms: Disc Partition, Extended Partitions, Logical Volume, partition, Partition Gap, partition table

In frequency-division multiplexing (FDM), equipment used to provide system end-to-end carrier frequency synchronization and frequency accuracy of tones. Note: The following types of oscillators are used in the Defense Communications System FDM systems:
- Type 1 - A master carrier oscillator as an integral part of the multiplexer set.
- Type 2 - A submaster oscillator equipment or slave oscillator equipment as an integral part of the multiplexer set.
- Type 3 - An external master oscillator equipment that has extremely accurate and stable characteristics.
Synonym master oscillator.

ATIS - Cite This Source - This Definition
Browse Related Terms: automatic frequency control (AFC), crystal oscillator (XO), fractional frequency fluctuation, frequency fluctuation, frequency stability, master oscillator, quartz oscillator, sweep acquisition, synchronizing pilot, syntonization, tone