16 letters

neuroastrocytoma neuroborreliosis neurochoroiditis neurocirculatory neurocristopathy neuroelectricity neuroepithelioma neurogliomatosis neurohypophyseal neurohypophysial neurolinguistics neuromusculature neuropathologist neurophysiologic neuropsychiatric neuropsychologic neuropsychopathy neuroradiologist neuroretinopathy neurorthopterous neurosarcoidosis neurotransmitter neurovaccination neutrophilopenia

17 letters

necessitudinarian necroinflammation necrophytophagous nekrophytophagous neoconstructivism neoconstructivist neologoliferation neomineralization neotraditionalism neotraditionalist nephelometrically nephrohypertrophy nephrolithotomies nephropyelography nephropyeloplasty nephrosonephritis neurilemmosarcoma neuroaugmentation neurodegeneration Neurodegenerative neurofibromatosis neuromorphometric neuropathogenesis neuropathological neuropharmacology neurophysiologist neuropsychiatrist Neuropsychologist neuropsychopathic neuropterological neurosarcocleisis neurotherapeutics neurotransmission neurotransmitters

18 letters

necroentomophilous necrogranulomatous neovascularization nephrostolithotomy nephrotuberculosis nephroureterectomy Neurocysticercosis neuroembryological neuroendocrinology neurolabyrinthitis neuroleptanalgesia neuroleptanalgesic neurolymphomatosis neuroophthalmology neuropathogenicity neuropharmacologic neurophysiological neuropsychological

19 letters

neochymotrypsinogen Nephroblastomatosis nephroureterectasis neuraleptanesthesia neurocommunications neuroleptanesthesia neuroleptanesthetic neuroleptoanalgesia neuropharmacologist

20 letters

necrocoleopterophily neurochorioretinitis neuroendocrinologist neuropharmacological neurophysiologically neuropsychiatrically neuroroentgenography

21 letters

neuroimmunomodulation

22 letters

necrocoleopterophilous nevoxanthoendothelioma

23 letters

nephroureterocystectomy neuropsychopharmacology

24 letters

neuroencephalomyelopathy

Words with a ∙ are valid Scrabble words (SOWPODS word list)