Biochemistry

• Human leukocyte antigen
  Human leukocyte antigen
  The human leukocyte antigen system is the name of the major histocompatibility complex in humans. The super locus contains a large number of genes related to immune system function in humans. This group of genes resides on chromosome 6, and encodes cell-surface antigen-presenting proteins and...
  
  , a key part of the human immune system, or the paternity test based upon it
• Hyaluronic Acid
  Hyaluronan
  Hyaluronan is an anionic, nonsulfated glycosaminoglycan distributed widely throughout connective, epithelial, and neural tissues...
  
  , an important molecule that plays a role throughout the body's skin and connective tissues.

Computing

• High Level Architecture (simulation), a distributed computer simulation standard
• High Level Assembly
  High Level Assembly
  High Level Assembler is an assembly language developed by Randall Hyde. It allows the use of higher-level language constructs to aid both beginners and advanced assembly developers. It fully supports advanced data types and object-oriented assembly language programming...
  
  , an Intel 80x86 Assembly Language
  X86 assembly language
  x86 assembly language is a family of backward-compatible assembly languages, which provide some level of compatibility all the way back to the Intel 8008. x86 assembly languages are used to produce object code for the x86 class of processors, which includes Intel's Core series and AMD's Phenom and...
  
  , originally written as a teaching aide by Randall Hyde
  Randall Hyde
  Randall Hyde is best known as the author of , a popular book on assembly language programming. He created the Lisa assembler in the late 1970s and developed the High Level Assembly language....
  
  .
• High-level assembler
  High-level assembler
  High-level assemblers in computing are assemblers for assembly language that incorporate features found in high-level programming languages.Some high-level assemblers are Borland's TASM, Microsoft's MASM, IBM's HLASM , Alessandro Ghignola's Linoleum, and Niklaus Wirth's PL/360.High-level assemblers...
  
  , a generic term for assembly language
  Assembly language
  An assembly language is a low-level programming language for computers, microprocessors, microcontrollers, and other programmable devices. It implements a symbolic representation of the machine codes and other constants needed to program a given CPU architecture...
  
   translators that incorporate features found in modern high-level programming languages into an assembler.

Engineering

• Hydraulic Lash Adjuster, a device for maintaining zero valve clearance in an internal combustion engine.
• Hydraulic Launch Assist
  Hydraulic Launch Assist
  Hydraulic Launch Assist is a hydraulic hybrid regenerative braking system produced by the Eaton Corporation.It also is referred to as the HLA system.- Background:...
  
  , a hybrid powertrain used on heavy duty vehicles.

Misc

• Hapag-Lloyd Airlines, a German charter airline
• Hidden Lake Academy
  Hidden Lake Academy
  -History:The school was founded in 1994 by Dr. Leonard Buccelatto. It was intended to "fill the need for a specialty school to fill the gap between services of residential treatment centers and traditional boarding schools."-Program:...
  
  , a boarding school
• HLA (radio station)
  HLA (radio station)
  HLA is a time signal radio station in Daejeon, South Korea, operated by the Korea Research Institute of Standards and Science. Established on November 24, 1984, it transmits a 2 kW signal on 5 MHz...
  
  , a South Korea
  South Korea
  The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...
  
  n time signal
  Time signal
  A time signal is a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day.-Audible and visible time signals:...
  
   station
• Hot Lesbian Action, a term used by Eric Bischoff during his tenure in WWE in 2002

Politics

• House of Lords Act, a UK constitutional reform
• Human Life Amendment
  Human Life Amendment
  The Human Life Amendment is the name for any amendment to the United States Constitution that would have the effect of overturning Roe v. Wade, the Supreme Court decision that denied states the authority to prohibit abortion. Although all of these amendments are intended to overturn Roe v...
  
  , a proposed constitutional prohibition of abortion in the United States