The Movable Final -ν

A small group of very common words - the accusative articles τον / την, the negators δεν / μην, and έναν - carry a final -ν that appears or disappears according to the NEXT sound. The -ν is KEPT before a vowel and before the sounds that can absorb it: κ, π, τ, the pairs μπ, ντ, γκ, τσ, τζ, and the double consonants ξ, ψ. It is DROPPED before every other consonant (β, γ, δ, ζ, θ, λ, μ, ν, ρ, σ, φ, χ). So: την ντομάτα but τη λάμπα; δεν μπορώ but δε βλέπω. This is why the digraphs had to come first - the rule is stated in terms of them. One practical exception: masculine τον normally keeps its -ν whatever follows, because dropping it would leave το and blur masculine with neuter.