cecni.

Headword: 
cecni.
Principal English Translation: 

somewhere; some place; in another place; somewhere else; separate, apart

Orthographic Variants: 
oc cecni, oc no cecni, no cecni
IPAspelling: 
sekni
Alonso de Molina: 

cecni. en otra parte o lugar, o en cierta parte, o por si aparte. aduerbio.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 15v. col. 1. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

CECNI in some particular place, apart / en otra parte o lugar, o en cierta parte, o por si aparte (M) See CECCĀN.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 27.

Horacio Carochi / English: 

cecni = in one place
Horacio Carochi, S.J., Grammar of the Mexican language with an explanation of its adverbs (1645), translated and edited with commentary by James Lockhart, UCLA Latin American Studies Volume 89 (Stanford: Stanford University Press, UCLA Latin American Center Publications, 2001), 338-41, 499.

Andrés de Olmos: 

en otra parte, por etc.
Andrés de Olmos, Arte para aprender la lengua Mexicana, ed. Rémi Siméon, facsimile edition ed. Miguel León-Portilla (Guadalajara: Edmundo Aviña Levy, 1972), 188.

Attestations from sources in English: 

inic cecni atlhuelican = 1st, Atluelican (Coyoacan, mid-sixteenth c.)
Beyond the Codices, eds. Arthur J.O. Anderson, Frances Berdan, and James Lockhart (Los Angeles: UCLA Latin American Center, 1976), Doc. 26, 160–161.

ynic cecni = first (Coyoacan, mid-sixteenth c.)
Beyond the Codices, eds. Arthur J.O. Anderson, Frances Berdan, and James Lockhart (Los Angeles: UCLA Latin American Center, 1976), Doc. 26, 158–159.

yn cecni huel ycihuatal quicahuilitiuh quimacatiuh yn itatzin ynantzin = this parcel is truly her woman's-land that her father and mother bequeathed and gave her (Coyoacan, 1575)
Beyond the Codices, eds. Arthur J.O. Anderson, Frances Berdan, and James Lockhart (Los Angeles: UCLA Latin American Center, 1976), Doc. 21, 116–117.

niman quicalaqui cecni oztoc = then he made him enter a cave in a certain place (early seventeenth century, Central Mexico)
Louise M. Burkhart, Before Guadalupe: The Virgin Mary in Early Colonial Nahuatl Literature, Institute for Mesoamerican Studies Monograph 13 (Albany: University at Albany, 2001), 139.

auh niman omotlatlalili omonetolti ynic cecni teopan = and then he solved and vowed that he would shut himself up in a temple in a certain place (early seventeenth century, Central Mexico)
Louise M. Burkhart, Before Guadalupe: The Virgin Mary in Early Colonial Nahuatl Literature, Institute for Mesoamerican Studies Monograph 13 (Albany: University at Albany, 2001), 140.

çeçecni tlacatecvlocalco = the diverse houses of the devil.
Fray Bernardino de Sahagún, Primeros Memoriales, ed. Thelma D. Sullivan, et al. (Norman: University of Oklahoma Press, 1997), 117.