As for the alien names, they all (almost) seem to have some real life counterpart that is oddly similar to them.
The Granger; A farmer. Considering the alien base is alive, Granger is a suitable name for our builder and maid.
The Dretch is.. well.. yeah..
The Basilisk is a fabled reptile residing in the arabian deserts who is said to be so deadly anything that smelled it's breath would pass away.
The Marauder is a marauder; It is Tremulous' raiding class.
The Dragoon; The dragoon is a heavily armed cavalry-man in early European armies. They were fast, agile, and very deadly.
The Tyrant; Tyrants are oppresive leaders who lead through scaring their people into following them. Personally, when I'm wall-jumping around with my raider and I see a 'rant coming at me, I get the fuck out of the way.
Overmind; Can be extrapolated as being a supreme ruler, perhaps the center of a hivemind like society, much like the Borg queen.
Acid Tube; A tube that is full of, or conists of acid.
Egg; An egg.
Trapper; It traps..
Hive; A structure used by bees, wasps, or other related insects for a home.
Barricade; A barricade; A barrier.
Hovel; A small area used for living.
Booster; In medical terms, a booster is a secondary shot of vaccination after the primary to increase effectiveness. You can stand on a booster to renew your poison even if it's not done yet (in some mods). A booster is also a supporter.. In tremulous it certainly supports the aliens; It heals them and makes them stronger.
Now, onto human weapons and technology...
Helmet; Come on, guess.
Light Armor; Armor that is light-weight, and most likely flexible.
Med-kit; A medical kit.
Battle Suit; A suit or exoskeleton designed to withstand the harshness of battle.
Medipad; A pad or base designed for medical purposes.
Defence Computer; A computer designed to be the motherboard for an area's defences.
Armoury; A "collection of resources."
Reactor; A device in which a reaction takes place. I'm sure there's particles bouncing around inside that big purple hunk o' metal to power your base.
MG Turret; A machine-gun turret. Turret implies that it's stationary and mounted. Machine-gun implies that it fires high speed projectiles.
Tesla Generator; A tesla coil; "a step-up transformer with an air core; used to produce high voltages at high frequencies."
Construction kit; A kit used for construction.
Rifle; A rifle.
Shotgun; A shotgun.
Lasgun; Well, shit. I don't know.
Mass Driver; A device that drives mass; shoots a projectile.
Pulse Rifle; A pulse is a rythmic expansion and contraction, for example, that of your heart. I'm stuck on this one.
Chaingun; A gun that is chainfed, not clipfed. Allows for huge amounts of ammo to be fired at once.
Flamethrower; A device that propels fire.
Lucifer Cannon; Lucifer is latin for "light bearer". Bet you didn't know that.
Grenade; It's a freaking grenade.