5 letters:
benak, benic, genic, senac

6 letters:
-genic, beneke, deneke, denike, fenech, fennec, fennek, fennic, henoch, krenek, krenik, penick, phenic, renick, zenick

7 letters:
behenic, benecke, bennick, dennoch, domenic, ethenic, eugenic, galenic, gerenuk, henneke, hennick, karenic, komenic, pennick, pennock, rennick, sirenic, sphenic, splenic, sthenic, vennick

8 letters:
anogenic, asplenic, asthenic, biogenic, congenic, diogenic, dysgenic, ecumenic, erogenic, exogenic, hellenic, isogenic, jaenicke, mnemenic, myogenic, orogenic, otogenic, oxygenic, phocenic, pyogenic, ruthenic, syngenic, syntenic, trigenic, zoogenic

9 letters:
abiogenic, acnegenic, acrogenic, aerogenic, agnogenic, algogenic, allogenic, antigenic, atmogenic, authentic, autogenic, biligenic, brennecke, cacogenic, catogenic, cryogenic, cytogenic, demogenic, echogenic, endogenic, ergogenic, gelogenic, homogenic, hypogenic, ketogenic, linolenic, lipogenic, lysogenic, metagenic, mitogenic, monogenic, nosogenic, oecumenic, oncogenic, ontogenic, paragenic, parthenic, pedogenic, polygenic, pyrogenic, renogenic, saracenic, telegenic, toxigenic, when nick, xenogenic, zymogenic

10 letters:
acidogenic, adipogenic, allergenic, amasthenic, amylogenic, androgenic, angiogenic, anxiogenic, audiogenic, authigenic, cariogenic, carpogenic, clonogenic, collagenic, cosmogenic, crinogenic, cyanogenic, diphygenic, diplogenic, ectrogenic, emetogenic, erotogenic, estrogenic, ethnogenic, extragenic, florigenic, glucogenic, glycogenic, hydrogenic, hypnogenic, iatrogenic, intergenic, intragenic, lactogenic, mediagenic, multigenic, myasthenic, myelogenic, naphthenic, necrogenic, neurogenic, obesogenic, orexigenic, orthogenic, osteogenic, pathogenic, peptogenic, phagedenic, photogenic, phylogenic, phytogenic, protogenic, pythogenic, radiogenic, rhizogenic, saprogenic, sociogenic, sporogenic, subphrenic, thyrogenic, transgenic, typhogenic

11 letters:
adaptogenic, atherogenic, calisthenic, calorigenic, cardiogenic, chromogenic, clastogenic, comedogenic, cryptogenic, demosthenic, embryogenic, entheogenic, epeirogenic, gametogenic, gastrogenic, goitrogenic, gynecogenic, hebephrenic, hematogenic, hepatogenic, heterogenic, hyposthenic, icterogenic, immunogenic, keratogenic, kinetogenic, knismogenic, lymphogenic, megasthenic, metasthenic, morphogenic, nephrogenic, odontogenic, oestrogenic, organogenic, panhellenic, pantothenic, perisplenic, phlogogenic, physiogenic, plasmagenic, pleurogenic, psychogenic, pyretogenic, somatogenic, teratogenic, terebilenic, thermogenic, toxicogenic, tumorigenic, ulcerogenic, undecylenic, xanthogenic

12 letters:
amphisbaenic, anisosthenic, anorexigenic, bronchogenic, callisthenic, cancerigenic, cancerogenic, carcinogenic, criminogenic, deuterogenic, diabetogenic, electrogenic, erythrogenic, fibrinogenic, haematogenic, hypersthenic, hysterogenic, isoantigenic, leukemogenic, metallogenic, methanogenic, microsthenic, neo-hellenic, neurasthenic, oligophrenic, pan-hellenic, phanerogenic, philhellenic, rachitogenic, reflexogenic, thrombogenic, vitellogenic, volcanogenic

13 letters:
anthropogenic, bacteriogenic, bronchiogenic, eclamptogenic, epileptogenic, esthesiogenic, gastrophrenic, gastrosplenic, nonallergenic, nonpathogenic, parthenogenic, progestogenic, psychasthenic, schizophrenic, spermatogenic, steroidogenic

14 letters:
aesthesiogenic, agglutinogenic, antiallergenic, antiangiogenic, arrhythmogenic, cocarcinogenic, crystallogenic, cytopathogenic, electrophrenic, hallucinogenic, hypoallergenic, indo-saracenic, musculophrenic, non-allergenic, noncomedogenic, pancreatogenic, phosphorogenic

15 letters:
enterotoxigenic, hypo-allergenic

16 letters:
anticarcinogenic, encephalitogenic, enteropathogenic, michelle jenneke

17 letters:
pericardiophrenic

18 letters:
jocelyn gourvennec

5 letters:
hemic

6 letters:
anemic, chemic, haemic

7 letters:
anaemic, endemic, polemic

8 letters:
academic, alchemic, azotemic, epidemic, pandemic, systemic

9 letters:
blastemic, epistemic

11 letters:
sarcolemmic