Birdnest may refer to:

• Bird nest - For birds
• Birdnest wiring - Electronic interconnection used for prototyping and high frequency applications
• Birdnest Records - Swedish punk record company

• Fixed Base Operator
• Fixed Bed Nuclear Reactor
• Fixed Channel Allocation
• Fixed channel allocation
• Fixed charge
• Fixed cog
• Fixed coordinate system
• Fixed Cost
• Fixed costs
• Fixed displacement compressor
• Fixed-dose combination (antiretroviral)
• Fixed-dose procedure
• Fixed drug eruption
• Fixed-effect model
• Fixed effect model
• Fixed effects
• Fixed Effects estimator
• Fixed effects estimator
• Fixed-effects model
• Fixed effects model
• Fixed effects model/version 2
• Fixed end moment
• Fixed end moments
• Fixed exchange rate systems
• Fixed expression