later
Latinside
About This Root
The root later comes from Latin latus (genitive lateris), meaning "the side" or "the flank" — the part of a body, a building, or a battlefield that is neither front nor back. A Roman soldier guarded his latus; a building had its latera. From this single idea of "the side," English built a tidy family of words, almost all about how many sides something has, or which side of something you are dealing with.
The base member is lateral (latus + -al = "of the side"). It means "sideways" — a lateral movement goes to the side, not forward; lateral thinking approaches a problem from the side instead of head-on. From there, prefixes simply count the sides:
- bi- (two) + later = bilateral: having two sides, hence "two-party." A bilateral agreement is between two countries.
- multi- (many) + later = multilateral: many-sided, "many parties." Multilateral talks involve several nations.
- uni- (one) + later = unilateral: one-sided. A unilateral decision is made by one side alone, without consulting the others.
- quadri- (four) + later = quadrilateral: a four-sided figure (geometry's square, rectangle, trapezoid).
- equi- (equal) + later = equilateral: equal-sided (the equilateral triangle).
The one member that has drifted is collateral (con- "together/alongside" + later = "side by side"). What runs beside the main thing is secondary to it: collateral relatives are your side-branches of the family (cousins, not direct ancestors); collateral damage is harm that happens off to the side of the intended target; and in finance, collateral is the asset you set beside a loan as backup security — if you default, the lender takes it. The shared thread is always "off to the side, accompanying the main thing."
One important warning about look-alikes. This root later (Latin latus "side") has nothing to do with the lat- you see in relate, translate, collate, and dilate. That other lāt- is the past participle of ferre ("to carry / bring") — relate = carry back, translate = carry across. They are spelled almost identically but are completely separate origins (homographs from different roots). A quick test: if the meaning is about sides, edges, or how many parties, it's the "side" later; if it's about carrying or bringing something, it's the ferre one.
Think of a quadrilateral in math class — a four-sided shape. Every later word is counting or pointing at sides: bilateral (two sides), multilateral (many sides), unilateral (one side acting alone), collateral (off to the side). Warning: re-late / trans-late are NOT in this family — that lat means "carry."
Core Words Deep Dive
The few words from this family worth telling in full — one by one.
The base word that everything else is built on: latus 'side' + -al = 'of the side,' i.e. sideways. The literal sense (a lateral pass in football, lateral roots of a plant) is straightforward, but the famous use is metaphorical: lateral thinking, coined by Edward de Bono, means attacking a problem from the side instead of marching at it head-on. Same image — you move sideways instead of forward.
bi- (two) + later (side) = 'two-sided,' which in diplomacy and trade means 'between two parties.' A bilateral agreement binds exactly two countries; contrast multilateral (many) and unilateral (one). The anatomical sense survives too: bilateral symmetry means the left and right sides mirror each other.
uni- (one) + later (side) = 'one-sided.' The key nuance isn't 'has one side' but 'done by one side alone, without the others' consent.' A unilateral ceasefire, a unilateral decision — one party acts on its own. That faint disapproval ('you didn't consult us') is what separates it from the neutral bilateral/multilateral.
con- (together, alongside) + later (side) = 'side by side.' Whatever runs beside the main thing is secondary: collateral relatives are family side-branches; collateral damage is harm beside the intended target; and in finance, collateral is the asset placed beside a loan as backup — default, and the lender seizes it. One root, three registers (family, military, money), all meaning 'off to the side.'
Related Roots
Two roots share the spelling lat-. This root (Latin latus) means 'side': lateral, bilateral, collateral. The other lat- is the past participle of ferre 'to carry': relate, translate, collate. Test: about sides/parties → this later; about carrying/bringing → the ferre one.
cost- (Latin costa 'rib, side') also names the side of the body — costal means 'of the ribs,' intercostal 'between the ribs.' Both later and cost point at the flank, but later went abstract (sides of a deal, sides of a polygon) while cost stayed anatomical.
Associated Words · 5
bilateral
Involving two sides or parties equally; a two-party meeting
collateral
An asset pledged as loan security; secondary or accompanying
lateral
Of or relating to the side; sideways
multilateral
Involving three or more countries or parties
quadrilateral
A four-sided polygon; having four sides